2.8.29 spline

Contents

Brief Information

Perform cubic spline interpolation/extrapolation of XY data

Command Line Usage

1. spline ix:=Col(3) iy:=(Col(1), Col(2));

2. spline ix:=Col(3) iy:=Col(2) ox:=Col(4);

X-Function Execution Options

Please refer to the page for additional option switches when accessing the x-function from script

Variables

Display
Name 		Variable
Name 		I/O
and
Type 		Default
Value 		Description
X Values to Interpolate ix

Input

vector

<unassigned>
 Specifies the X values to be interpolated on the spline
Input iy

Input

XYRange

<active>
 The input XY range data to be interpolated
Boundary boundary

Input

int

notaknot
 Boundary condition only available in cubic spline method

Option list:

  • natural:Natural
2nd derivatives are 0 on both end
  • notaknot:Not-A-Knot
3rd derivatives are continuous on the second and last-second point
Result of Interpolation ox

Output

vector

<new>
 Specifies the column to save output interpolated Y values on the spline
Coefficients coef

Output

vector

<optional>
 Whether or not to output spline coefficients

Description

This function performs Cubic spline interpolation on XY range data. You should specify the X coordinates on the spline, and it will output a vector contains the interpolated values on these X values.

Examples

  1. Import Interpolation.dat on \Samples\Mathematics folder.
  2. Highlight column B and type spline -d on the command window to bring up the dialog.
  3. On the X Value to Interpolate drop-down list, select Col(C).
  4. Click OK to do interpolation on column C values.

Algorithm

Detail algorithms please read the help of interp1.

Related X-Functions

interp1, interp1xy, interp1q, bspline

Keywords:interpolation, extrapolation