Subroutine Type

Utility/Data Access

Definition

Use the FITSPL spline fitting method to return the interpolated value or n-th derivative of the interpolated value of the Reference_Spline element.

Use

The function can be called by any user-defined subroutine.

Calling Syntax

Fortran

CALL FITSPL(XVAL, ZVAL, ID, IORD, ARRAY, ERRFLG)

C

c_fitspl(xval, zval, id, iord, array, errflg)

Python

[value, eflag] = py_fitspl(x, z, id, iord)

MATLAB

[value, eflag] = m_fitspl(x, z, id, iord)

Input Arguments

double precision] XVAL

The independent x value at which the FITSPL spline function is supposed to interpolate the output value.

[double precision] ZVAL

The independent z value at which the FITSPL spline function is supposed to interpolate the output value for the 3-D spline data

[integer] ID

The identifier of the corresponding user defined Reference_Spline element.

[logical] IORD

The order of derivative returned by the FITSPL function.

Output Values

[double precision] ARRAY

The vector output value of dimension 3.

If IORD is 0, then the returned values are the interpolated values of y.

If IORD is 1, then the returned values are the derivatives of y with respect to x and z.

If IORD is 2, then the output array contains the second derivatives of y with respect to xx, xz, and zz, respectively.

[logical] ERRFLG

The logical variable that is returned to the calling subroutine and that indicates the success of the FITSPL function call.