Naming refactoring

kmath-commons/src/main/kotlin/space/kscience/kmath/commons/transform/Transformations.kt

@@ -10,28 +10,18 @@ import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.map
 import org.apache.commons.math3.transform.*
 import space.kscience.kmath.complex.Complex
-import space.kscience.kmath.operations.SuspendBufferTransform
+import space.kscience.kmath.operations.BufferTransform
 import space.kscience.kmath.streaming.chunked
 import space.kscience.kmath.streaming.spread
-import space.kscience.kmath.structures.Buffer
+import space.kscience.kmath.structures.*
-import space.kscience.kmath.structures.DoubleBuffer
-import space.kscience.kmath.structures.VirtualBuffer
-import space.kscience.kmath.structures.asBuffer
-
 
 /**
- * Streaming and buffer transformations
+ * Streaming and buffer transformations with Commons-math algorithms
  */
 public object Transformations {
-    private fun Buffer<Complex>.toArray(): Array<org.apache.commons.math3.complex.Complex> =
+    private fun Buffer<Complex>.toCmComplexArray(): Array<org.apache.commons.math3.complex.Complex> =
         Array(size) { org.apache.commons.math3.complex.Complex(get(it).re, get(it).im) }
 
-    private fun Buffer<Double>.asArray() = if (this is DoubleBuffer) {
-        array
-    } else {
-        DoubleArray(size) { i -> get(i) }
-    }
-
     /**
      * Create a virtual buffer on top of array
      */
@@ -43,70 +33,67 @@ public object Transformations {
     public fun fourier(
         normalization: DftNormalization = DftNormalization.STANDARD,
         direction: TransformType = TransformType.FORWARD,
-    ): SuspendBufferTransform<Complex, Complex> = {
+    ): BufferTransform<Complex, Complex> = BufferTransform {
-        FastFourierTransformer(normalization).transform(it.toArray(), direction).asBuffer()
+        FastFourierTransformer(normalization).transform(it.toCmComplexArray(), direction).asBuffer()
     }
 
     public fun realFourier(
         normalization: DftNormalization = DftNormalization.STANDARD,
         direction: TransformType = TransformType.FORWARD,
-    ): SuspendBufferTransform<Double, Complex> = {
+    ): BufferTransform<Double, Complex> = BufferTransform {
-        FastFourierTransformer(normalization).transform(it.asArray(), direction).asBuffer()
+        FastFourierTransformer(normalization).transform(it.toDoubleArray(), direction).asBuffer()
     }
 
     public fun sine(
         normalization: DstNormalization = DstNormalization.STANDARD_DST_I,
         direction: TransformType = TransformType.FORWARD,
-    ): SuspendBufferTransform<Double, Double> = {
+    ): BufferTransform<Double, Double> = DoubleBufferTransform {
-        FastSineTransformer(normalization).transform(it.asArray(), direction).asBuffer()
+        FastSineTransformer(normalization).transform(it.array, direction).asBuffer()
     }
 
     public fun cosine(
         normalization: DctNormalization = DctNormalization.STANDARD_DCT_I,
         direction: TransformType = TransformType.FORWARD,
-    ): SuspendBufferTransform<Double, Double> = {
+    ): BufferTransform<Double, Double> = BufferTransform {
-        FastCosineTransformer(normalization).transform(it.asArray(), direction).asBuffer()
+        FastCosineTransformer(normalization).transform(it.toDoubleArray(), direction).asBuffer()
     }
 
     public fun hadamard(
         direction: TransformType = TransformType.FORWARD,
-    ): SuspendBufferTransform<Double, Double> = {
+    ): BufferTransform<Double, Double> = DoubleBufferTransform {
-        FastHadamardTransformer().transform(it.asArray(), direction).asBuffer()
+        FastHadamardTransformer().transform(it.array, direction).asBuffer()
     }
 }
 
 /**
  * Process given [Flow] with commons-math fft transformation
  */
-@FlowPreview
+public fun Flow<Buffer<Complex>>.fft(
-public fun Flow<Buffer<Complex>>.FFT(
     normalization: DftNormalization = DftNormalization.STANDARD,
     direction: TransformType = TransformType.FORWARD,
 ): Flow<Buffer<Complex>> {
     val transform = Transformations.fourier(normalization, direction)
-    return map { transform(it) }
+    return map(transform::transform)
 }
 
-@FlowPreview
 @JvmName("realFFT")
-public fun Flow<Buffer<Double>>.FFT(
+public fun Flow<Buffer<Double>>.fft(
     normalization: DftNormalization = DftNormalization.STANDARD,
     direction: TransformType = TransformType.FORWARD,
 ): Flow<Buffer<Complex>> {
     val transform = Transformations.realFourier(normalization, direction)
-    return map(transform)
+    return map(transform::transform)
 }
 
 /**
  * Process a continuous flow of real numbers in FFT splitting it in chunks of [bufferSize].
  */
-@FlowPreview
 @JvmName("realFFT")
-public fun Flow<Double>.FFT(
+public fun Flow<Double>.fft(
     bufferSize: Int = Int.MAX_VALUE,
     normalization: DftNormalization = DftNormalization.STANDARD,
     direction: TransformType = TransformType.FORWARD,
-): Flow<Complex> = chunked(bufferSize).FFT(normalization, direction).spread()
+): Flow<Complex> = chunked(bufferSize).fft(normalization, direction).spread()
 
 /**
  * Map a complex flow into real flow by taking real part of each number

kmath-complex/src/commonMain/kotlin/space/kscience/kmath/complex/Complex.kt

@@ -193,7 +193,6 @@ public object ComplexField :
  * @property re The real part.
  * @property im The imaginary part.
  */
-@OptIn(UnstableKMathAPI::class)
 public data class Complex(val re: Double, val im: Double) {
     public constructor(re: Number, im: Number) : this(re.toDouble(), im.toDouble())
     public constructor(re: Number) : this(re.toDouble(), 0.0)

kmath-core/src/commonMain/kotlin/space/kscience/kmath/operations/bufferOperation.kt

@@ -9,14 +9,18 @@ import space.kscience.kmath.misc.UnstableKMathAPI
 import space.kscience.kmath.structures.*
 
 /**
- * Typealias for buffer transformations.
+ * Type alias for buffer transformations.
  */
-public typealias BufferTransform<T, R> = (Buffer<T>) -> Buffer<R>
+public fun interface BufferTransform<T, R> {
+    public fun transform(arg: Buffer<T>): Buffer<R>
+}
 
-/**
+///**
- * Typealias for buffer transformations with suspend function.
+// * Type alias for buffer transformations with suspend function.
- */
+// */
-public typealias SuspendBufferTransform<T, R> = suspend (Buffer<T>) -> Buffer<R>
+//public fun interface SuspendBufferTransform<T, R>{
+//    public suspend fun transform(arg: Buffer<T>): Buffer<R>
+//}
 
 
 /**

kmath-core/src/commonMain/kotlin/space/kscience/kmath/structures/DoubleBuffer.kt

@@ -5,6 +5,7 @@
 
 package space.kscience.kmath.structures
 
+import space.kscience.kmath.operations.BufferTransform
 import kotlin.jvm.JvmInline
 
 /**
@@ -28,7 +29,7 @@ public value class DoubleBuffer(public val array: DoubleArray) : MutableBuffer<D
 
     override fun toString(): String = Buffer.toString(this)
 
-    public companion object{
+    public companion object {
         public fun zero(size: Int): DoubleBuffer = DoubleArray(size).asBuffer()
     }
 }
@@ -40,7 +41,8 @@ public value class DoubleBuffer(public val array: DoubleArray) : MutableBuffer<D
  * The function [init] is called for each array element sequentially starting from the first one.
  * It should return the value for a buffer element given its index.
  */
-public inline fun DoubleBuffer(size: Int, init: (Int) -> Double): DoubleBuffer = DoubleBuffer(DoubleArray(size) { init(it) })
+public inline fun DoubleBuffer(size: Int, init: (Int) -> Double): DoubleBuffer =
+    DoubleBuffer(DoubleArray(size) { init(it) })
 
 /**
  * Returns a new [DoubleBuffer] of given elements.
@@ -51,10 +53,15 @@ public fun DoubleBuffer(vararg doubles: Double): DoubleBuffer = DoubleBuffer(dou
  * Returns a new [DoubleArray] containing all the elements of this [Buffer].
  */
 public fun Buffer<Double>.toDoubleArray(): DoubleArray = when (this) {
-    is DoubleBuffer -> array.copyOf()
+    is DoubleBuffer -> array
     else -> DoubleArray(size, ::get)
 }
 
+public fun Buffer<Double>.toDoubleBuffer(): DoubleBuffer = when (this) {
+    is DoubleBuffer -> this
+    else -> DoubleArray(size, ::get).asBuffer()
+}
+
 /**
  * Returns [DoubleBuffer] over this array.
  *
@@ -62,3 +69,10 @@ public fun Buffer<Double>.toDoubleArray(): DoubleArray = when (this) {
  * @return the new buffer.
  */
 public fun DoubleArray.asBuffer(): DoubleBuffer = DoubleBuffer(this)
+
+
+public fun interface DoubleBufferTransform : BufferTransform<Double, Double> {
+    public fun transform(arg: DoubleBuffer): DoubleBuffer
+
+    override fun transform(arg: Buffer<Double>): DoubleBuffer = arg.toDoubleBuffer()
+}

kmath-core/src/jvmTest/kotlin/space/kscience/kmath/misc/JBigTest.kt

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2018-2022 KMath contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package space.kscience.kmath.misc
+
+import org.junit.jupiter.api.Test
+import space.kscience.kmath.operations.JBigDecimalField
+import kotlin.test.assertEquals
+import kotlin.test.assertNotEquals
+
+class JBigTest {
+
+    @Test
+    fun testExact() = with(JBigDecimalField) {
+        assertNotEquals(0.3, 0.1 + 0.2)
+        assertEquals(one * 0.3, one * 0.1 + one * 0.2)
+    }
+}

kmath-coroutines/src/commonMain/kotlin/space/kscience/kmath/streaming/BufferFlow.kt

@@ -5,8 +5,10 @@
 
 package space.kscience.kmath.streaming
 
-import kotlinx.coroutines.FlowPreview
+import kotlinx.coroutines.flow.Flow
-import kotlinx.coroutines.flow.*
+import kotlinx.coroutines.flow.asFlow
+import kotlinx.coroutines.flow.flatMapConcat
+import kotlinx.coroutines.flow.flow
 import space.kscience.kmath.chains.BlockingDoubleChain
 import space.kscience.kmath.structures.Buffer
 import space.kscience.kmath.structures.BufferFactory
@@ -20,7 +22,6 @@ public fun <T> Buffer<T>.asFlow(): Flow<T> = iterator().asFlow()
 /**
  * Flat map a [Flow] of [Buffer] into continuous [Flow] of elements
  */
-@FlowPreview
 public fun <T> Flow<Buffer<T>>.spread(): Flow<T> = flatMapConcat { it.asFlow() }
 
 /**

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/DoubleTensor.kt

@@ -28,7 +28,7 @@ public class OffsetDoubleBuffer(
     override fun get(index: Int): Double = source[index + offset]
 
     /**
-     * Copy only a part of buffer that belongs to this tensor
+     * Copy only a part of buffer that belongs to this [OffsetDoubleBuffer]
      */
     override fun copy(): DoubleBuffer = source.array.copyOfRange(offset, offset + size).asBuffer()
 

kmath-tensors/src/commonMain/kotlin/space/kscience/kmath/tensors/core/DoubleTensorAlgebra.kt

@@ -59,20 +59,16 @@ public open class DoubleTensorAlgebra :
         }
     }
 
-    public inline fun Tensor<Double>.mapIndexedInPlace(operation: (IntArray, Double) -> Double) {
+    public inline fun Tensor<Double>.mapIndexedInPlace(operation: DoubleField.(IntArray, Double) -> Double) {
-        indices.forEach { set(it, operation(it, get(it))) }
+        indices.forEach { set(it, DoubleField.operation(it, get(it))) }
     }
 
     @Suppress("OVERRIDE_BY_INLINE")
     final override inline fun StructureND<Double>.mapIndexed(transform: DoubleField.(index: IntArray, Double) -> Double): DoubleTensor {
-        val tensor = this.asDoubleTensor()
+        return copyToTensor().apply { mapIndexedInPlace(transform) }
-        //TODO remove additional copy
-        val buffer = DoubleBuffer(tensor.source.size) {
-            DoubleField.transform(tensor.indices.index(it), tensor.source[it])
-        }
-        return DoubleTensor(tensor.shape, buffer)
     }
 
+
     @Suppress("OVERRIDE_BY_INLINE")
     final override inline fun zip(
         left: StructureND<Double>,
@@ -92,7 +88,7 @@ public open class DoubleTensorAlgebra :
 
     public inline fun StructureND<Double>.reduceElements(transform: (DoubleBuffer) -> Double): Double =
         transform(asDoubleTensor().source.copy())
-    //TODO do we need protective copy?
+    //TODO Add read-only DoubleBuffer wrapper. To avoid protective copy
 
     override fun StructureND<Double>.valueOrNull(): Double? {
         val dt = asDoubleTensor()

kmath-trajectory/src/commonMain/kotlin/space/kscience/kmath/trajectory/DubinsPath.kt

@@ -23,64 +23,65 @@ internal fun Pose2D.getTangentCircles(radius: Double): Pair<Circle2D, Circle2D>
     return Circle2D(vector(x - dX, y + dY), radius) to Circle2D(vector(x + dX, y - dY), radius)
 }
 
-internal fun leftOuterTangent(a: Circle2D, b: Circle2D): StraightSegment = outerTangent(a, b, ArcSegment.Direction.LEFT)
+internal fun leftOuterTangent(a: Circle2D, b: Circle2D): StraightTrajectory = outerTangent(a, b, CircleTrajectory.Direction.LEFT)
 
-internal fun rightOuterTangent(a: Circle2D, b: Circle2D): StraightSegment = outerTangent(a, b,
+internal fun rightOuterTangent(a: Circle2D, b: Circle2D): StraightTrajectory = outerTangent(a, b,
-    ArcSegment.Direction.RIGHT
+    CircleTrajectory.Direction.RIGHT
 )
 
-private fun outerTangent(a: Circle2D, b: Circle2D, side: ArcSegment.Direction): StraightSegment = with(Euclidean2DSpace){
+private fun outerTangent(a: Circle2D, b: Circle2D, side: CircleTrajectory.Direction): StraightTrajectory = with(Euclidean2DSpace){
-    val centers = StraightSegment(a.center, b.center)
+    val centers = StraightTrajectory(a.center, b.center)
     val p1 = when (side) {
-        ArcSegment.Direction.LEFT -> vector(
+        CircleTrajectory.Direction.LEFT -> vector(
             a.center.x - a.radius * cos(centers.theta),
             a.center.y + a.radius * sin(centers.theta)
         )
-        ArcSegment.Direction.RIGHT -> vector(
+        CircleTrajectory.Direction.RIGHT -> vector(
             a.center.x + a.radius * cos(centers.theta),
             a.center.y - a.radius * sin(centers.theta)
         )
     }
-    return StraightSegment(
+    return StraightTrajectory(
         p1,
         vector(p1.x + (centers.end.x - centers.start.x), p1.y + (centers.end.y - centers.start.y))
     )
 }
 
-internal fun leftInnerTangent(base: Circle2D, direction: Circle2D): StraightSegment? =
+internal fun leftInnerTangent(base: Circle2D, direction: Circle2D): StraightTrajectory? =
-    innerTangent(base, direction, ArcSegment.Direction.LEFT)
+    innerTangent(base, direction, CircleTrajectory.Direction.LEFT)
 
-internal fun rightInnerTangent(base: Circle2D, direction: Circle2D): StraightSegment? =
+internal fun rightInnerTangent(base: Circle2D, direction: Circle2D): StraightTrajectory? =
-    innerTangent(base, direction, ArcSegment.Direction.RIGHT)
+    innerTangent(base, direction, CircleTrajectory.Direction.RIGHT)
 
-private fun innerTangent(base: Circle2D, direction: Circle2D, side: ArcSegment.Direction): StraightSegment? = with(Euclidean2DSpace){
+private fun innerTangent(base: Circle2D, direction: Circle2D, side: CircleTrajectory.Direction): StraightTrajectory? = with(Euclidean2DSpace){
-    val centers = StraightSegment(base.center, direction.center)
+    val centers = StraightTrajectory(base.center, direction.center)
     if (centers.length < base.radius * 2) return null
     val angle = theta(
         when (side) {
-            ArcSegment.Direction.LEFT -> centers.theta + acos(base.radius * 2 / centers.length)
+            CircleTrajectory.Direction.LEFT -> centers.theta + acos(base.radius * 2 / centers.length)
-            ArcSegment.Direction.RIGHT -> centers.theta - acos(base.radius * 2 / centers.length)
+            CircleTrajectory.Direction.RIGHT -> centers.theta - acos(base.radius * 2 / centers.length)
         }
     )
     val dX = base.radius * sin(angle)
     val dY = base.radius * cos(angle)
     val p1 = vector(base.center.x + dX, base.center.y + dY)
     val p2 = vector(direction.center.x - dX, direction.center.y - dY)
-    return StraightSegment(p1, p2)
+    return StraightTrajectory(p1, p2)
 }
 
 internal fun theta(theta: Double): Double = (theta + (2 * PI)) % (2 * PI)
 
+@Suppress("DuplicatedCode")
 public class DubinsPath(
-    public val a: ArcSegment,
+    public val a: CircleTrajectory,
     public val b: Trajectory,
-    public val c: ArcSegment,
+    public val c: CircleTrajectory,
 ) : CompositeTrajectory(listOf(a,b,c)) {
 
     public val type: TYPE = TYPE.valueOf(
         arrayOf(
             a.direction.name[0],
-            if (b is ArcSegment) b.direction.name[0] else 'S',
+            if (b is CircleTrajectory) b.direction.name[0] else 'S',
             c.direction.name[0]
         ).toCharArray().concatToString()
     )
@@ -106,56 +107,98 @@ public class DubinsPath(
         public fun shortest(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath =
             all(start, end, turningRadius).minBy { it.length }
 
-        public fun rlr(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath? = with(Euclidean2DSpace){
+        public fun rlr(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath? = with(Euclidean2DSpace) {
             val c1 = start.getRightCircle(turningRadius)
             val c2 = end.getRightCircle(turningRadius)
-            val centers = StraightSegment(c1.center, c2.center)
+            val centers = StraightTrajectory(c1.center, c2.center)
             if (centers.length > turningRadius * 4) return null
 
-            var theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
+            val firstVariant = run {
-            var dX = turningRadius * sin(theta)
+                var theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
-            var dY = turningRadius * cos(theta)
+                var dX = turningRadius * sin(theta)
-            val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
+                var dY = turningRadius * cos(theta)
-            val e = Circle2D(p, turningRadius)
+                val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
-            val p1 = vector(c1.center.x + dX, c1.center.y + dY)
+                val e = Circle2D(p, turningRadius)
-            theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
+                val p1 = vector(c1.center.x + dX, c1.center.y + dY)
-            dX = turningRadius * sin(theta)
+                theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
-            dY = turningRadius * cos(theta)
+                dX = turningRadius * sin(theta)
-            val p2 = vector(e.center.x + dX, e.center.y + dY)
+                dY = turningRadius * cos(theta)
-            val a1 = ArcSegment.of(c1.center, start, p1, ArcSegment.Direction.RIGHT)
+                val p2 = vector(e.center.x + dX, e.center.y + dY)
-            val a2 = ArcSegment.of(e.center, p1, p2, ArcSegment.Direction.LEFT)
+                val a1 = CircleTrajectory.of(c1.center, start, p1, CircleTrajectory.Direction.RIGHT)
-            val a3 = ArcSegment.of(c2.center, p2, end, ArcSegment.Direction.RIGHT)
+                val a2 = CircleTrajectory.of(e.center, p1, p2, CircleTrajectory.Direction.LEFT)
-            return DubinsPath(a1, a2, a3)
+                val a3 = CircleTrajectory.of(c2.center, p2, end, CircleTrajectory.Direction.RIGHT)
+                DubinsPath(a1, a2, a3)
+            }
+
+            val secondVariant = run {
+                var theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
+                var dX = turningRadius * sin(theta)
+                var dY = turningRadius * cos(theta)
+                val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
+                val e = Circle2D(p, turningRadius)
+                val p1 = vector(c1.center.x + dX, c1.center.y + dY)
+                theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
+                dX = turningRadius * sin(theta)
+                dY = turningRadius * cos(theta)
+                val p2 = vector(e.center.x + dX, e.center.y + dY)
+                val a1 = CircleTrajectory.of(c1.center, start, p1, CircleTrajectory.Direction.RIGHT)
+                val a2 = CircleTrajectory.of(e.center, p1, p2, CircleTrajectory.Direction.LEFT)
+                val a3 = CircleTrajectory.of(c2.center, p2, end, CircleTrajectory.Direction.RIGHT)
+                DubinsPath(a1, a2, a3)
+            }
+
+            return if (firstVariant.length < secondVariant.length) firstVariant else secondVariant
         }
 
-        public fun lrl(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath?= with(Euclidean2DSpace) {
+        public fun lrl(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath? = with(Euclidean2DSpace) {
             val c1 = start.getLeftCircle(turningRadius)
             val c2 = end.getLeftCircle(turningRadius)
-            val centers = StraightSegment(c1.center, c2.center)
+            val centers = StraightTrajectory(c1.center, c2.center)
             if (centers.length > turningRadius * 4) return null
 
-            var theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
+            val firstVariant = run {
-            var dX = turningRadius * sin(theta)
+                var theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
-            var dY = turningRadius * cos(theta)
+                var dX = turningRadius * sin(theta)
-            val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
+                var dY = turningRadius * cos(theta)
-            val e = Circle2D(p, turningRadius)
+                val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
-            val p1 = vector(c1.center.x + dX, c1.center.y + dY)
+                val e = Circle2D(p, turningRadius)
-            theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
+                val p1 = vector(c1.center.x + dX, c1.center.y + dY)
-            dX = turningRadius * sin(theta)
+                theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
-            dY = turningRadius * cos(theta)
+                dX = turningRadius * sin(theta)
-            val p2 = vector(e.center.x + dX, e.center.y + dY)
+                dY = turningRadius * cos(theta)
-            val a1 = ArcSegment.of(c1.center, start, p1, ArcSegment.Direction.LEFT)
+                val p2 = vector(e.center.x + dX, e.center.y + dY)
-            val a2 = ArcSegment.of(e.center, p1, p2, ArcSegment.Direction.RIGHT)
+                val a1 = CircleTrajectory.of(c1.center, start, p1, CircleTrajectory.Direction.LEFT)
-            val a3 = ArcSegment.of(c2.center, p2, end, ArcSegment.Direction.LEFT)
+                val a2 = CircleTrajectory.of(e.center, p1, p2, CircleTrajectory.Direction.RIGHT)
-            return DubinsPath(a1, a2, a3)
+                val a3 = CircleTrajectory.of(c2.center, p2, end, CircleTrajectory.Direction.LEFT)
+                DubinsPath(a1, a2, a3)
+            }
+
+            val secondVariant = run{
+                var theta = theta(centers.theta - acos(centers.length / (turningRadius * 4)))
+                var dX = turningRadius * sin(theta)
+                var dY = turningRadius * cos(theta)
+                val p = vector(c1.center.x + dX * 2, c1.center.y + dY * 2)
+                val e = Circle2D(p, turningRadius)
+                val p1 = vector(c1.center.x + dX, c1.center.y + dY)
+                theta = theta(centers.theta + acos(centers.length / (turningRadius * 4)))
+                dX = turningRadius * sin(theta)
+                dY = turningRadius * cos(theta)
+                val p2 = vector(e.center.x + dX, e.center.y + dY)
+                val a1 = CircleTrajectory.of(c1.center, start, p1, CircleTrajectory.Direction.LEFT)
+                val a2 = CircleTrajectory.of(e.center, p1, p2, CircleTrajectory.Direction.RIGHT)
+                val a3 = CircleTrajectory.of(c2.center, p2, end, CircleTrajectory.Direction.LEFT)
+                DubinsPath(a1, a2, a3)
+            }
+
+            return if (firstVariant.length < secondVariant.length) firstVariant else secondVariant
         }
 
         public fun rsr(start: Pose2D, end: Pose2D, turningRadius: Double): DubinsPath {
             val c1 = start.getRightCircle(turningRadius)
             val c2 = end.getRightCircle(turningRadius)
             val s = leftOuterTangent(c1, c2)
-            val a1 = ArcSegment.of(c1.center, start, s.start, ArcSegment.Direction.RIGHT)
+            val a1 = CircleTrajectory.of(c1.center, start, s.start, CircleTrajectory.Direction.RIGHT)
-            val a3 = ArcSegment.of(c2.center, s.end, end, ArcSegment.Direction.RIGHT)
+            val a3 = CircleTrajectory.of(c2.center, s.end, end, CircleTrajectory.Direction.RIGHT)
             return DubinsPath(a1, s, a3)
         }
 
@@ -163,8 +206,8 @@ public class DubinsPath(
             val c1 = start.getLeftCircle(turningRadius)
             val c2 = end.getLeftCircle(turningRadius)
             val s = rightOuterTangent(c1, c2)
-            val a1 = ArcSegment.of(c1.center, start, s.start, ArcSegment.Direction.LEFT)
+            val a1 = CircleTrajectory.of(c1.center, start, s.start, CircleTrajectory.Direction.LEFT)
-            val a3 = ArcSegment.of(c2.center, s.end, end, ArcSegment.Direction.LEFT)
+            val a3 = CircleTrajectory.of(c2.center, s.end, end, CircleTrajectory.Direction.LEFT)
             return DubinsPath(a1, s, a3)
         }
 
@@ -174,8 +217,8 @@ public class DubinsPath(
             val s = rightInnerTangent(c1, c2)
             if (s == null || c1.center.distanceTo(c2.center) < turningRadius * 2) return null
 
-            val a1 = ArcSegment.of(c1.center, start, s.start, ArcSegment.Direction.RIGHT)
+            val a1 = CircleTrajectory.of(c1.center, start, s.start, CircleTrajectory.Direction.RIGHT)
-            val a3 = ArcSegment.of(c2.center, s.end, end, ArcSegment.Direction.LEFT)
+            val a3 = CircleTrajectory.of(c2.center, s.end, end, CircleTrajectory.Direction.LEFT)
             return DubinsPath(a1, s, a3)
         }
 
@@ -185,8 +228,8 @@ public class DubinsPath(
             val s = leftInnerTangent(c1, c2)
             if (s == null || c1.center.distanceTo(c2.center) < turningRadius * 2) return null
 
-            val a1 = ArcSegment.of(c1.center, start, s.start, ArcSegment.Direction.LEFT)
+            val a1 = CircleTrajectory.of(c1.center, start, s.start, CircleTrajectory.Direction.LEFT)
-            val a3 = ArcSegment.of(c2.center, s.end, end, ArcSegment.Direction.RIGHT)
+            val a3 = CircleTrajectory.of(c2.center, s.end, end, CircleTrajectory.Direction.RIGHT)
             return DubinsPath(a1, s, a3)
         }
     }

kmath-trajectory/src/commonMain/kotlin/space/kscience/kmath/trajectory/Trajectory.kt

@@ -19,7 +19,7 @@ public sealed interface Trajectory {
 /**
  * Straight path segment. The order of start and end defines the direction
  */
-public data class StraightSegment(
+public data class StraightTrajectory(
     internal val start: DoubleVector2D,
     internal val end: DoubleVector2D,
 ) : Trajectory {
@@ -31,7 +31,7 @@ public data class StraightSegment(
 /**
  * An arc segment
  */
-public data class ArcSegment(
+public data class CircleTrajectory(
     public val circle: Circle2D,
     public val start: Pose2D,
     public val end: Pose2D,
@@ -68,7 +68,7 @@ public data class ArcSegment(
     }
 
     public companion object {
-        public fun of(center: DoubleVector2D, start: DoubleVector2D, end: DoubleVector2D, direction: Direction): ArcSegment {
+        public fun of(center: DoubleVector2D, start: DoubleVector2D, end: DoubleVector2D, direction: Direction): CircleTrajectory {
             fun calculatePose(
                 vector: DoubleVector2D,
                 theta: Double,
@@ -81,11 +81,11 @@ public data class ArcSegment(
                 }
             )
 
-            val s1 = StraightSegment(center, start)
+            val s1 = StraightTrajectory(center, start)
-            val s2 = StraightSegment(center, end)
+            val s2 = StraightTrajectory(center, end)
             val pose1 = calculatePose(start, s1.theta, direction)
             val pose2 = calculatePose(end, s2.theta, direction)
-            return ArcSegment(Circle2D(center, s1.length), pose1, pose2)
+            return CircleTrajectory(Circle2D(center, s1.length), pose1, pose2)
         }
     }
 }

kmath-trajectory/src/commonTest/kotlin/space/kscience/kmath/trajectory/Math.kt

@@ -17,12 +17,12 @@ fun Double.radiansToDegrees() = this * 180 / PI
 fun Double.equalFloat(other: Double) = abs(this - other) < maxFloatDelta
 fun Pose2D.equalsFloat(other: Pose2D) = x.equalFloat(other.x) && y.equalFloat(other.y) && theta.equalFloat(other.theta)
 
-fun StraightSegment.inverse() = StraightSegment(end, start)
+fun StraightTrajectory.inverse() = StraightTrajectory(end, start)
-fun StraightSegment.shift(shift: Int, width: Double): StraightSegment = with(Euclidean2DSpace){
+fun StraightTrajectory.shift(shift: Int, width: Double): StraightTrajectory = with(Euclidean2DSpace){
     val dX = width * sin(inverse().theta)
     val dY = width * sin(theta)
 
-    return StraightSegment(
+    return StraightTrajectory(
         vector(start.x - dX * shift, start.y - dY * shift),
         vector(end.x - dX * shift, end.y - dY * shift)
     )

kmath-trajectory/src/commonTest/kotlin/space/kscience/kmath/trajectory/dubins/DubinsTests.kt

@@ -16,7 +16,7 @@ class DubinsTests {
 
     @Test
     fun dubinsTest() = with(Euclidean2DSpace){
-        val straight = StraightSegment(vector(0.0, 0.0), vector(100.0, 100.0))
+        val straight = StraightTrajectory(vector(0.0, 0.0), vector(100.0, 100.0))
         val lineP1 = straight.shift(1, 10.0).inverse()
 
         val start = Pose2D(straight.end, straight.theta)
@@ -45,12 +45,12 @@ class DubinsTests {
             assertTrue(end.equalsFloat(path.c.end))
 
             // Not working, theta double precision inaccuracy
-            if (path.b is ArcSegment) {
+            if (path.b is CircleTrajectory) {
-                val b = path.b as ArcSegment
+                val b = path.b as CircleTrajectory
                 assertTrue(path.a.end.equalsFloat(b.start))
                 assertTrue(path.c.start.equalsFloat(b.end))
-            } else if (path.b is StraightSegment) {
+            } else if (path.b is StraightTrajectory) {
-                val b = path.b as StraightSegment
+                val b = path.b as StraightTrajectory
                 assertTrue(path.a.end.equalsFloat(Pose2D(b.start, b.theta)))
                 assertTrue(path.c.start.equalsFloat(Pose2D(b.end, b.theta)))
             }

kmath-trajectory/src/commonTest/kotlin/space/kscience/kmath/trajectory/segments/ArcTests.kt

@@ -8,7 +8,7 @@ package space.kscience.kmath.trajectory.segments
 import space.kscience.kmath.geometry.Circle2D
 import space.kscience.kmath.geometry.Euclidean2DSpace
 import space.kscience.kmath.geometry.circumference
-import space.kscience.kmath.trajectory.ArcSegment
+import space.kscience.kmath.trajectory.CircleTrajectory
 import space.kscience.kmath.trajectory.radiansToDegrees
 import kotlin.test.Test
 import kotlin.test.assertEquals
@@ -18,7 +18,7 @@ class ArcTests {
     @Test
     fun arcTest() = with(Euclidean2DSpace){
         val circle = Circle2D(vector(0.0, 0.0), 2.0)
-        val arc = ArcSegment.of(circle.center, vector(-2.0, 0.0), vector(0.0, 2.0), ArcSegment.Direction.RIGHT)
+        val arc = CircleTrajectory.of(circle.center, vector(-2.0, 0.0), vector(0.0, 2.0), CircleTrajectory.Direction.RIGHT)
         assertEquals(circle.circumference / 4, arc.length, 1.0)
         assertEquals(0.0, arc.start.theta.radiansToDegrees())
         assertEquals(90.0, arc.end.theta.radiansToDegrees())

kmath-trajectory/src/commonTest/kotlin/space/kscience/kmath/trajectory/segments/LineTests.kt

@@ -6,7 +6,7 @@
 package space.kscience.kmath.trajectory.segments
 
 import space.kscience.kmath.geometry.Euclidean2DSpace
-import space.kscience.kmath.trajectory.StraightSegment
+import space.kscience.kmath.trajectory.StraightTrajectory
 import space.kscience.kmath.trajectory.radiansToDegrees
 import kotlin.math.pow
 import kotlin.math.sqrt
@@ -17,7 +17,7 @@ class LineTests {
 
     @Test
     fun lineTest() = with(Euclidean2DSpace){
-        val straight = StraightSegment(vector(0.0, 0.0), vector(100.0, 100.0))
+        val straight = StraightTrajectory(vector(0.0, 0.0), vector(100.0, 100.0))
         assertEquals(sqrt(100.0.pow(2) + 100.0.pow(2)), straight.length)
         assertEquals(45.0, straight.theta.radiansToDegrees())
     }
@@ -25,13 +25,13 @@ class LineTests {
     @Test
     fun lineAngleTest() = with(Euclidean2DSpace){
         //val zero = Vector2D(0.0, 0.0)
-        val north = StraightSegment(Euclidean2DSpace.zero, vector(0.0, 2.0))
+        val north = StraightTrajectory(Euclidean2DSpace.zero, vector(0.0, 2.0))
         assertEquals(0.0, north.theta.radiansToDegrees())
-        val east = StraightSegment(Euclidean2DSpace.zero, vector(2.0, 0.0))
+        val east = StraightTrajectory(Euclidean2DSpace.zero, vector(2.0, 0.0))
         assertEquals(90.0, east.theta.radiansToDegrees())
-        val south = StraightSegment(Euclidean2DSpace.zero, vector(0.0, -2.0))
+        val south = StraightTrajectory(Euclidean2DSpace.zero, vector(0.0, -2.0))
         assertEquals(180.0, south.theta.radiansToDegrees())
-        val west = StraightSegment(Euclidean2DSpace.zero, vector(-2.0, 0.0))
+        val west = StraightTrajectory(Euclidean2DSpace.zero, vector(-2.0, 0.0))
         assertEquals(270.0, west.theta.radiansToDegrees())
     }
 }