Mercurial > octave-nkf
view libcruft/slatec-fn/pchst.f @ 16088:b29b10fbb744 stable release-3-6-4
Version 3.6.4 released.
* configure.ac (AC_INIT): Version is now 3.6.4.
(OCTAVE_RELEASE_DATE): Now 2013-02-21.
author | John W. Eaton <jwe@octave.org> |
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date | Thu, 21 Feb 2013 15:17:54 -0500 |
parents | 82be108cc558 |
children |
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*DECK PCHST REAL FUNCTION PCHST (ARG1, ARG2) C***BEGIN PROLOGUE PCHST 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 C C**End C C DECLARE ARGUMENTS. C REAL ARG1, ARG2 C C DECLARE LOCAL VARIABLES. C REAL ONE, ZERO SAVE ZERO, ONE DATA ZERO /0./, ONE /1./ C C PERFORM THE TEST. C C***FIRST EXECUTABLE STATEMENT PCHST PCHST = SIGN(ONE,ARG1) * SIGN(ONE,ARG2) IF ((ARG1.EQ.ZERO) .OR. (ARG2.EQ.ZERO)) PCHST = ZERO C RETURN C------------- LAST LINE OF PCHST FOLLOWS ------------------------------ END