Subroutine Type

Utility/General

Definition

Evaluates a STEP function via a cubic polynomial approximation.

Use

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

Calling Syntax

Fortran

CALL STEP (X, X0, H0, X1, H1, IORD, VALUE, ERRFLG)

C

c_step(x, x0, h0, x1, h1, iord, value, errflg)

Python

[value, errflg] = py_step(x, x0, h0, x1, h1, irod)

MATLAB

[value, errflg] = m_step(x, x0, h0, x1, h1, irod)

Input Arguments

X [double precision]

The independent variable.  For example, to specify time as the independent variable, specify X as TIME.

X0 [double precision]

The X value at which the STEP function begins.

H0 [double precision]

The value of the STEP function at X0

X1 [double precision]

The X value at which the STEP function ends.

H1 [double precision]

The value of the STEP function at X1.

IORD [integer]

The order of the derivative that STEP has to return.  Order can be 0, 1 or 2.

Output Values

Value [integer]

A value that the subroutine returns.

Errflg [logical]

A (true or false) variable that STEP returns to the calling subroutine.  If STEP detects an error while calling the subroutine, it sets the error flag to true.