Version:

Last Modified: June 25, 2019

Returns a spline interpolated value at a single value given the tabulated values (*x*[*i*],
*y*[*i*]) and the second derivatives of the cubic spline interpolating function that this node obtains from the Spline Interpolant node.

Tabulated value of the dependent variable.

This input accepts a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

Tabulated value of the independent variable.

This input accepts a double-precision, floating-point number or a 1D array of double-precision, floating-point numbers.

Second derivative of the cubic spline interpolating function.

You can obtain
**interpolant**
from the
Spline Interpolant
node.

When
**x**
and
**y**
are 1D arrays of double-precision, floating-point numbers, the number of elements in
**x**,
**y**, and
**interpolant**
must be the same. Otherwise, this node sets
**yi**
to
NaN
and returns an error.

When
**x**
and
**y**
are double-precision, floating-point numbers, the number of elements in
**interpolant**
must equal
**sample length**. Otherwise, this node sets
**yi**
to zero and returns an error.

A single value.
**xi**
must fall within the range [**x**
_{0},
**x**
_{
n
- 1}].

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an
**error in**
input and an
**error out**
output so that the node can respond to and communicate errors that occur while code is running. The value of
**error in**
specifies whether an error occurred before the node runs. Most nodes respond to values of
**error in**
in a standard, predictable way.

**Default:
**No error

Length of each set of data. The node performs computation for each set of data.

**sample length**
must be greater than zero.

This input is available only if you wire a double-precision, floating-point number to
**x**
or
**y**.

**Default:
**100

Cubic spline interpolation of
*f*
at the single value.

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

**error in**
input and an
**error out**
output so that the node can respond to and communicate errors that occur while code is running. The value of
**error in**
specifies whether an error occurred before the node runs. Most nodes respond to values of
**error in**
in a standard, predictable way.

The points are formed by the input arrays
**x**
and
**y**.

On the interval [*x*
_{
i
},
*x*
_{
i
+ 1}], the following equation defines the interpolation value
**yi**.

$\mathrm{yi}=A{y}_{i}+B{y}_{i+1}+C{y\prime \prime}_{i}+D{y\prime \prime}_{i+1}$

where

$A=\frac{{x}_{i+1}-x}{{x}_{i+1}-{x}_{i}}$

$B=1-A$

$C=\frac{1}{6}({A}^{3}-A){({x}_{i+1}-{x}_{i})}^{2}$

$D=\frac{1}{6}({B}^{3}-B){({x}_{i+1}-{x}_{i})}^{2}$

**Where This Node Can Run:
**

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application