This function evaluates the exponentially scaled complementary error function.

Function Return Value

ERFCE — Function value.   (Output)

Required Arguments

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

FORTRAN 90 Interface

Generic:                              ERFCE (X)

Specific:                             The specific interface names are S_ERFCE and D_ERFCE.

FORTRAN 77 Interface

Single:                                ERFCE (X)

Double:                              The double precision function name is DERFCE.

Description

The function ERFCE(X) computes

where erfc(x) is the complementary error function. See ERFC for its definition.

To prevent the answer from underflowing, x must be greater than

where b =  AMACH(2) is the largest representable floating-point number.

Comments

Informational error

Type           Code

2                   1          The function underflows because X is too large.

Example

In this example, ERFCE(1.0) = e1.0 erfc(1.0) is computed and printed.

 

      USE ERFCE_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

!                                 Declare variables

      INTEGER    NOUT

      REAL       VALUE, X

!                                 Compute

      X     = 1.0

      VALUE = ERFCE(X)

!                                 Print the results

      CALL UMACH (2, NOUT)

      WRITE (NOUT,99999) X, VALUE

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

      END

Output

 

ERFCE( 1.000) =  0.428

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