pchst.f
REAL FUNCTION PCHST (ARG1, ARG2)
C***BEGIN PROLOGUE PCHST
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Warning: this routine is not intended to be user-callable.
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C***SUBSIDIARY
C***PURPOSE PCHIP Sign-Testing Routine
C***LIBRARY SLATEC (PCHIP)
C***TYPE SINGLE PRECISION (PCHST-S, DPCHST-D)
C***AUTHOR Fritsch, F. N., (LLNL)
C***DESCRIPTION
C
C PCHST: PCHIP Sign-Testing Routine.
C
C Returns:
C -1. if ARG1 and ARG2 are of opposite sign.
C 0. if either argument is zero.
C +1. if ARG1 and ARG2 are of the same sign.
C
C The object is to do this without multiplying ARG1*ARG2, to avoid
C possible over/underflow problems.
C
C Fortran intrinsics used: SIGN.
C
C***SEE ALSO PCHCE, PCHCI, PCHCS, PCHIM
C***ROUTINES CALLED (NONE)
C***REVISION HISTORY (YYMMDD)
C 811103 DATE WRITTEN
C 820805 Converted to SLATEC library version.
C 870813 Minor cosmetic changes.
C 890411 Added SAVE statements (Vers. 3.2).
C 890411 REVISION DATE from Version 3.2
C 891214 Prologue converted to Version 4.0 format. (BAB)
C 900328 Added TYPE section. (WRB)
C 910408 Updated AUTHOR and DATE WRITTEN sections in prologue. (WRB)
C 930503 Improved purpose. (FNF)
C***END PROLOGUE PCHST