function [pchstresult,arg1,arg2]=pchst(arg1,arg2);
pchstresult=[];
persistent firstCall one zero ; if isempty(firstCall),firstCall=1;end;
;
%***BEGIN PROLOGUE PCHST
%***SUBSIDIARY
%***PURPOSE PCHIP Sign-Testing Routine
%***LIBRARY SLATEC (PCHIP)
%***TYPE SINGLE PRECISION (PCHST-S, DPCHST-D)
%***AUTHOR Fritsch, F. N., (LLNL)
%***DESCRIPTION
%
% PCHST: PCHIP Sign-Testing Routine.
%
% Returns:
% -1. if ARG1 and ARG2 are of opposite sign.
% 0. if either argument is zero.
% +1. if ARG1 and ARG2 are of the same sign.
%
% The object is to do this without multiplying ARG1*ARG2, to avoid
% possible over/underflow problems.
%
% Fortran intrinsics used: SIGN.
%
%***SEE ALSO PCHCE, PCHCI, PCHCS, PCHIM
%***ROUTINES CALLED (NONE)
%***REVISION HISTORY (YYMMDD)
% 811103 DATE WRITTEN
% 820805 Converted to SLATEC library version.
% 870813 Minor cosmetic changes.
% 890411 Added SAVE statements (Vers. 3.2).
% 890411 REVISION DATE from Version 3.2
% 891214 Prologue converted to Version 4.0 format. (BAB)
% 900328 Added TYPE section. (WRB)
% 910408 Updated AUTHOR and DATE WRITTEN sections in prologue. (WRB)
% 930503 Improved purpose. (FNF)
%***end PROLOGUE PCHST
%
%**end
%
% DECLARE ARGUMENTS.
%
%
% DECLARE LOCAL VARIABLES.
%
if isempty(one), one=0; end;
if isempty(zero), zero=0; end;
if firstCall, zero=[0.]; end;
if firstCall, one=[1.]; end;
firstCall=0;
%
% PERFORM THE TEST.
%
%***FIRST EXECUTABLE STATEMENT PCHST
pchstresult = (abs(one).*sign(arg1)).*(abs(one).*sign(arg2));
if((arg1==zero) ||(arg2==zero) )
pchstresult = zero;
end;
%
%------------- LAST LINE OF PCHST FOLLOWS ------------------------------
csnil=dbstack(1); csnil=csnil(1).name(1)~='@';
if csnil&&~isempty(inputname(2)), assignin('caller','FUntemp',arg2); evalin('caller',[inputname(2),'=FUntemp;']); end
if csnil&&~isempty(inputname(1)), assignin('caller','FUntemp',arg1); evalin('caller',[inputname(1),'=FUntemp;']); end
end
%DECK PCHSW
