ERF

This function evaluates the error function.

Function Return Value

ERF — Function value. (Output)

Required Arguments

X — Argument for which the function value is desired. (Input)

FORTRAN 90 Interface

Generic: ERF (X)

Specific: The specific interface names are S_ERF and D_ERF.

FORTRAN 77 Interface

Single: ERF (X)

Double: The double precision function name is DERF.

Description

The error function, erf(x), is defined to be

 

All values of x are legal.

 

Figure 1,  Plot of erf (x)

Example

In this example, erf(1.0) is computed and printed.

 

USE ERF_INT

USE UMACH_INT

 

IMPLICIT NONE

! Declare variables

INTEGER NOUT

REAL VALUE, X

! Compute

X = 1.0

VALUE = ERF(X)

! Print the results

CALL UMACH (2, NOUT)

WRITE (NOUT,99999) X, VALUE

99999 FORMAT (' ERF(', F6.3, ') = ', F6.3)

END

Output

 

ERF( 1.000) = 0.843