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cdf_51.c
Go to the documentation of this file.00001 #include "cdflib.h" 00002 void dzror(int *status,double *x,double *fx,double *xlo, 00003 double *xhi,unsigned long *qleft,unsigned long *qhi) 00004 /* 00005 ********************************************************************** 00006 00007 void dzror(int *status,double *x,double *fx,double *xlo, 00008 double *xhi,unsigned long *qleft,unsigned long *qhi) 00009 00010 Double precision ZeRo of a function -- Reverse Communication 00011 00012 00013 Function 00014 00015 00016 Performs the zero finding. STZROR must have been called before 00017 this routine in order to set its parameters. 00018 00019 00020 Arguments 00021 00022 00023 STATUS <--> At the beginning of a zero finding problem, STATUS 00024 should be set to 0 and ZROR invoked. (The value 00025 of other parameters will be ignored on this call.) 00026 00027 When ZROR needs the function evaluated, it will set 00028 STATUS to 1 and return. The value of the function 00029 should be set in FX and ZROR again called without 00030 changing any of its other parameters. 00031 00032 When ZROR has finished without error, it will return 00033 with STATUS 0. In that case (XLO,XHI) bound the answe 00034 00035 If ZROR finds an error (which implies that F(XLO)-Y an 00036 F(XHI)-Y have the same sign, it returns STATUS -1. In 00037 this case, XLO and XHI are undefined. 00038 INTEGER STATUS 00039 00040 X <-- The value of X at which F(X) is to be evaluated. 00041 DOUBLE PRECISION X 00042 00043 FX --> The value of F(X) calculated when ZROR returns with 00044 STATUS = 1. 00045 DOUBLE PRECISION FX 00046 00047 XLO <-- When ZROR returns with STATUS = 0, XLO bounds the 00048 inverval in X containing the solution below. 00049 DOUBLE PRECISION XLO 00050 00051 XHI <-- When ZROR returns with STATUS = 0, XHI bounds the 00052 inverval in X containing the solution above. 00053 DOUBLE PRECISION XHI 00054 00055 QLEFT <-- .TRUE. if the stepping search terminated unsucessfully 00056 at XLO. If it is .FALSE. the search terminated 00057 unsucessfully at XHI. 00058 QLEFT is LOGICAL 00059 00060 QHI <-- .TRUE. if F(X) .GT. Y at the termination of the 00061 search and .FALSE. if F(X) .LT. Y at the 00062 termination of the search. 00063 QHI is LOGICAL 00064 00065 ********************************************************************** 00066 */ 00067 { 00068 E0001(0,status,x,fx,xlo,xhi,qleft,qhi,NULL,NULL,NULL,NULL); 00069 } /* END */
