#include "cdflib.h"
void dstzr(double *zxlo,double *zxhi,double *zabstl,double *zreltl)
/*
**********************************************************************
void dstzr(double *zxlo,double *zxhi,double *zabstl,double *zreltl)
Double precision SeT ZeRo finder - Reverse communication version
Function
Sets quantities needed by ZROR. The function of ZROR
and the quantities set is given here.
Concise Description - Given a function F
find XLO such that F(XLO) = 0.
More Precise Description -
Input condition. F is a double precision function of a single
double precision argument and XLO and XHI are such that
F(XLO)*F(XHI) .LE. 0.0
If the input condition is met, QRZERO returns .TRUE.
and output values of XLO and XHI satisfy the following
F(XLO)*F(XHI) .LE. 0.
ABS(F(XLO) .LE. ABS(F(XHI)
ABS(XLO-XHI) .LE. TOL(X)
where
TOL(X) = MAX(ABSTOL,RELTOL*ABS(X))
If this algorithm does not find XLO and XHI satisfying
these conditions then QRZERO returns .FALSE. This
implies that the input condition was not met.
Arguments
XLO --> The left endpoint of the interval to be
searched for a solution.
XLO is DOUBLE PRECISION
XHI --> The right endpoint of the interval to be
for a solution.
XHI is DOUBLE PRECISION
ABSTOL, RELTOL --> Two numbers that determine the accuracy
of the solution. See function for a
precise definition.
ABSTOL is DOUBLE PRECISION
RELTOL is DOUBLE PRECISION
Method
Algorithm R of the paper 'Two Efficient Algorithms with
Guaranteed Convergence for Finding a Zero of a Function'
by J. C. P. Bus and T. J. Dekker in ACM Transactions on
Mathematical Software, Volume 1, no. 4 page 330
(Dec. '75) is employed to find the zero of F(X)-Y.
**********************************************************************
*/
{
E0001(1,NULL,NULL,NULL,NULL,NULL,NULL,NULL,zabstl,zreltl,zxhi,zxlo);
} /* END */