This function evaluates a scaled function related to ERFC.

Function Return Value

CERFE — Complex function value.   (Output)

Required Arguments

Z — Complex argument for which the function value is desired.   (Input)

FORTRAN 90 Interface

Generic:                              CERFE (Z)

Specific:                             The specific interface names are C_CERFE and Z_CERFE.

FORTRAN 77 Interface

Complex:                            CERFE (Z)

Double complex:               The double  complex function name is ZERFE.

Description

Function CERFE is defined to be

Let b = AMACH(2) be the largest floating-point number. The argument z must satisfy

or else the value returned is zero. If the argument z does not satisfy (ℑz)2−(ℜz)2≤ log b, then b is returned. All other arguments are legal (Gautschi 1969, 1970).

Example

In this example, CERFE(2.5 + 2.5i) is computed and printed.

 

      USE CERFE_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

!                                 Declare variables

      INTEGER    NOUT

      COMPLEX    VALUE, Z

!                                 Compute

      Z     = (2.5, 2.5)

      VALUE = CERFE(Z)

!                                 Print the results

      CALL UMACH (2, NOUT)

      WRITE (NOUT,99999) Z, VALUE

99999 FORMAT (' CERFE(', F6.3, ',', F6.3, ') = (', &

           F6.3, ',', F6.3, ')')

      END

Output

 

CERFE( 2.500, 2.500) = ( 0.117, 0.108)

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