diff --git a/doc/contexts.md b/doc/contexts.md
new file mode 100644
index 000000000..df0ea4e1d
--- /dev/null
+++ b/doc/contexts.md
@@ -0,0 +1,3 @@
+# Context-oriented programming
+
+One of problems   
\ No newline at end of file
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/LUDecomposition.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/LUDecomposition.kt
index 223e63419..6a94042b7 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/LUDecomposition.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/linear/LUDecomposition.kt
@@ -198,7 +198,6 @@ class RealLUDecomposition(matrix: RealMatrix, private val singularityThreshold:
 /** Specialized solver.  */
 object RealLUSolver : LinearSolver<Double, DoubleField> {
 
-
     fun decompose(mat: Matrix<Double, DoubleField>, threshold: Double = 1e-11): RealLUDecomposition = RealLUDecomposition(mat, threshold)
 
     override fun solve(a: RealMatrix, b: RealMatrix): RealMatrix {
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt
index 8d3c01d28..46388edaf 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/operations/Complex.kt
@@ -6,12 +6,14 @@ package scientifik.kmath.operations
 object ComplexField : Field<Complex> {
     override val zero: Complex = Complex(0.0, 0.0)
 
+    override val one: Complex = Complex(1.0, 0.0)
+
+    val i = Complex(0.0, 1.0)
+
     override fun add(a: Complex, b: Complex): Complex = Complex(a.re + b.re, a.im + b.im)
 
     override fun multiply(a: Complex, k: Double): Complex = Complex(a.re * k, a.im * k)
 
-    override val one: Complex = Complex(1.0, 0.0)
-
     override fun multiply(a: Complex, b: Complex): Complex = Complex(a.re * b.re - a.im * b.im, a.re * b.im + a.im * b.re)
 
     override fun divide(a: Complex, b: Complex): Complex = Complex(a.re * b.re + a.im * b.im, a.re * b.im - a.im * b.re) / b.square
@@ -41,5 +43,16 @@ data class Complex(val re: Double, val im: Double) : FieldElement<Complex, Compl
     companion object {
 
     }
+}
 
-}
\ No newline at end of file
+fun Double.toComplex() = Complex(this, 0.0)
+
+operator fun Double.plus(c: Complex) = this.toComplex() + c
+
+operator fun Double.minus(c: Complex) = this.toComplex() - c
+
+operator fun Complex.plus(d: Double) = d + this
+
+operator fun Complex.minus(d: Double) = this - d.toComplex()
+
+operator fun Double.times(c: Complex) = Complex(c.re * this, c.im * this)
\ No newline at end of file
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt
index 69e8163c6..8bbb87057 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/Buffers.kt
@@ -68,8 +68,7 @@ class ArrayBuffer<T>(private val array: Array<T>) : MutableBuffer<T> {
 }
 
 inline class DoubleBuffer(private val array: DoubleArray) : MutableBuffer<Double> {
-    override val size: Int
-        get() = array.size
+    override val size: Int get() = array.size
 
     override fun get(index: Int): Double = array[index]
 
@@ -83,8 +82,7 @@ inline class DoubleBuffer(private val array: DoubleArray) : MutableBuffer<Double
 }
 
 inline class IntBuffer(private val array: IntArray) : MutableBuffer<Int> {
-    override val size: Int
-        get() = array.size
+    override val size: Int get() = array.size
 
     override fun get(index: Int): Int = array[index]
 
diff --git a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt
index f9521cf93..6e159c9dd 100644
--- a/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt
+++ b/kmath-core/src/commonMain/kotlin/scientifik/kmath/structures/NDStructure.kt
@@ -49,6 +49,9 @@ interface Strides {
      */
     fun index(offset: Int): IntArray
 
+    /**
+     * The size of linear buffer to accommodate all elements of ND-structure corresponding to strides
+     */
     val linearSize: Int
 
     /**