This function evaluates Dawson's function.

Function Return Value

DAWS — Function value.   (Output)

Required Arguments

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

FORTRAN 90 Interface

Generic:                              DAWS (X)

Specific:                             The specific interface names are S_DAWS and D_DAWS.

FORTRAN 77 Interface

Single:                                DAWS (X)

Double:                              The double precision function name is DDAWS.

Description

Dawson's function is defined to be

It is closely related to the error function for imaginary arguments.

So that Dawson's function does not underflow, |x| must be less than 1/(2s). Here, s = AMACH(1) is the smallest representable positive floating-point number.

Comments

Informational error

Type           Code

3                   2          The function underflows because the absolute value of X is too large .

The Dawson function is closely related to the error function for imaginary arguments.

Example

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

 

      USE DAWS_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

!                                 Declare variables

      INTEGER    NOUT

      REAL       VALUE, X

!                                 Compute

      X     = 1.0

      VALUE = DAWS(X)

!                                 Print the results

      CALL UMACH (2, NOUT)

      WRITE (NOUT,99999) X, VALUE

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

      END

Output

 

DAWS( 1.000) =  0.538

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