Add different ways to provide data for XY interpolator

kmath-functions/src/commonMain/kotlin/scientifik/kmath/interpolation/Interpolator.kt

@@ -3,6 +3,8 @@ package scientifik.kmath.interpolation
 import scientifik.kmath.functions.PiecewisePolynomial
 import scientifik.kmath.functions.value
 import scientifik.kmath.operations.Ring
+import scientifik.kmath.structures.Buffer
+import scientifik.kmath.structures.asBuffer
 
 interface Interpolator<X, Y> {
     fun interpolate(points: XYPointSet<X, Y>): (X) -> Y
@@ -18,4 +20,26 @@ interface PolynomialInterpolator<T : Comparable<T>> : Interpolator<T, T> {
     override fun interpolate(points: XYPointSet<T, T>): (T) -> T = { x ->
         interpolatePolynomials(points).value(algebra, x) ?: getDefaultValue()
     }
+}
+
+fun <T : Comparable<T>> PolynomialInterpolator<T>.interpolatePolynomials(
+    x: Buffer<T>,
+    y: Buffer<T>
+): PiecewisePolynomial<T> {
+    val pointSet = BufferXYPointSet(x, y)
+    return interpolatePolynomials(pointSet)
+}
+
+fun <T : Comparable<T>> PolynomialInterpolator<T>.interpolatePolynomials(
+    data: Map<T, T>
+): PiecewisePolynomial<T> {
+    val pointSet = BufferXYPointSet(data.keys.toList().asBuffer(), data.values.toList().asBuffer())
+    return interpolatePolynomials(pointSet)
+}
+
+fun <T : Comparable<T>> PolynomialInterpolator<T>.interpolatePolynomials(
+    data: List<Pair<T, T>>
+): PiecewisePolynomial<T> {
+    val pointSet = BufferXYPointSet(data.map { it.first }.asBuffer(), data.map { it.second }.asBuffer())
+    return interpolatePolynomials(pointSet)
 }

kmath-functions/src/commonMain/kotlin/scientifik/kmath/interpolation/LoessInterpolator.kt

@@ -1,4 +1,4 @@
-//package scientifik.kmath.interpolation
+package scientifik.kmath.interpolation
 //
 //import scientifik.kmath.functions.PiecewisePolynomial
 //import scientifik.kmath.operations.Ring