nan$(3F)                                                 nan$(3F)



NAME
     nan$, dnan$, cnan$, znan$, cdnan$  - generate IEEE signal-
     ling Not-a-Number bit patterns

SYNOPSIS
     real*4 r
     double precision d
     complex*8 c
     double complex z(5), z0

     data r / nan$() /, z / 5 * znan$() /

     d = dnan$()
     c = cnan$()
     z0 = cdnan$()

DESCRIPTION
     nan$, dnan$, cnan$ and znan$ are constant intrinsics gen-
     erating IEEE signalling Not-a-Number (NaN) bit patterns in
     single precision, double precision, single precision complex
     (real and imaginary portions each contain NaN) and double
     precision complex formats, respectively.  A constant intrin-
     sic is a special hf77 intrinsic which produces, at compile
     time, a constant that may be otherwise difficult or impossi-
     ble to represent using conventional constant syntax.

     These intrinsics may be used to initialize real and complex
     variables (via initialization statements or assignments) to
     values which are invalid if used in arithmetic operations,
     allowing users to quickly detect uses of otherwise unini-
     tialized variables.  The Diagnostics section of the hf77(1)
     man page contains further information on tracking down NaN
     exceptions, whether generated from executable code or from
     within hf77 itself.

     cdnan$ is identical to znan$.

CAUTIONS
     These intrinsics are all specific representations; there is
     no "generic" feature available.  The intrinsic appropriate
     to the data type of the receiving variable must be used.

SEE ALSO
     hf77(1).











Page 1                        CX/UX Hf77 Fortran Reference Manual