This function evaluates a function closely related to the hyperbolic cosine integral.

Function Return Value

CINH — Function value.    (Output)

Required Arguments

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

FORTRAN 90 Interface

Generic:                              CINH (X)

Specific:                             The specific interface names are S_CINH and D_CINH.

FORTRAN 77 Interface

Single:                                CINH (X)

Double:                              The double precision function name is DCINH.

Description

The alternate definition of the hyperbolic cosine integral, Cinh(x), is

 

For

where s = AMACH(1) is the smallest representable positive number, the result underflows. The argument x must be large enough that e−x/x does not underflow, and x must be small enough that ex does not overflow.

Comments

Informational error

Type   Code

2           1                  The function underflows because X is too small.

Example

In this example, Cinh(2.5) is computed and printed.

 

      USE CINH_INT

      USE UMACH_INT

 

      IMPLICIT   NONE

!                                 Declare variables

      INTEGER    NOUT

      REAL       VALUE, X

!                                 Compute

      X     = 2.5

      VALUE = CINH(X)

!                                 Print the results

      CALL UMACH (2, NOUT)

      WRITE (NOUT,99999) X, VALUE

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

      END

Output

 

CINH( 2.500) =  2.031

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