/[dtapublic]/projs/dtats/trunk/projs/2018/20180707_cgi_web_tools_aux_exe/subfunc_gcd.c

Diff of /projs/dtats/trunk/projs/2018/20180707_cgi_web_tools_aux_exe/subfunc_gcd.c

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-revision 170 by dashley,
Sun Jul  8 21:12:48 2018 UTC
+revision 172 by dashley,
Sun Jul  8 21:17:26 2018 UTC
 Line 1
- //$Header: /cvsroot/esrg/sfesrg/esrgnxpj/sfnthcgi0304/subfunc_gcd.c,v 1.5 2003/07/01 03:46:58 dtashley Exp $
+ //$Header$
  //
  //********************************************************************************
  //Copyright (C) 2003 David T. Ashley
  //********************************************************************************
  //This program or source file is free software; you can redistribute it and/or
  //modify it under the terms of the GNU General Public License as published by
  //the Free Software Foundation; either version 2 of the License, or (at your
  //option) any later version.
  //
  //This program or source file is distributed in the hope that it will
  //be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
  //MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //GNU General Public License for more details.
  //
  //You may have received a copy of the GNU General Public License
  //along with this program; if not, write to the Free Software
  //Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //
  //This module is the GCD subfunction of a general-purpose CGI-BIN program to support
  //number theory demonstration applications.
  //
  //INPUT PARAMETERS
  //----------------
  //The subfunction accepts two parameters, the integers whose GCD is to be
  //calculated.  There is substantial tolerance for invalid characters.
  //Naturally, the integers should be positive.
  //
  //OUTPUT RESULTS
  //--------------
  //The notation below gives the outputs of the program.  In some cases, [i] notation
  //is used to indicate line numbers.
  //
  //[01] An overall success or failure code for the operation.  Valid responses
  //     are:
  //        S      :  Success.
  //        EP1A   :  The first integer could not be parsed, which means it is ill-formatted.
  //        EP1B   :  The first integer was zero or negative.
  //        EP2A   :  The second integer could not be parsed, which means it is ill-formatted.
  //        EP2B   :  The second integer was zero or negative.
  //        EQ     :  Other or unspecified error.
  //
  //[02] The fully normalized first integer entered.  This means it has been
  //     stripped of all weird characters, etc.  This can be used by the
  //     PHP script to repopulate the form boxes.
  //[03] The fully normalized second integer entered.
  //
  //In the event that the status code indicates error, no further lines
  //will be written.
  //
  //[04] The round number of the application of Euclid's algorithm, starting
  //     at "1".
  //[05] "a".
  //[06] "b".
  //[07] a div b.
  //[08] a mod b.
  //[09] ... repeating sequence, starting back at [4] and repeating until a
  //     zero remainder.
  //[..] The GCD of the two integers.  This will be positive and
  //     contain no commas or extraneous characters.
  //[..] "S", indicating success.
  //
  //Note that as per the definition above, any valid non-error output from
  //this program will contain a number of lines which is a multiple of 5.
  //
  //The return value (exit code) from this subfunction is always 0.
  //
  #define MODULE_SUBFUNC_GCD
  #include <assert.h>
  #include <ctype.h>
  #include <stddef.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  #include <gmp.h>
  #include "auxfuncs.h"
  #include "subfunc_gcd.h"
  int SUBFUNC_GCD_main(int argc, char *argv[])
     {
     //Normalized first and second parameters (the integers).
     char *arg1;
     char *arg2;
     //GMP types to maintain the algorithm.
     int round;
     mpz_t alg_a, alg_b, alg_adivb, alg_amodb;
     //There must be an acceptable number of command-line arguments.
     if (argc != 4)
        {
        printf("EQ\n0\n0\n");
        return(0);
        }
     //Copy the command-line arguments to a safe place where we can manipulate them.
     //Leave 2 characters of space in case we assign a "0".
     arg1 = (char *)malloc((AUXFUNCS_size_t_max(1, strlen(argv[2])) + 1) * sizeof(char));
     arg2 = (char *)malloc((AUXFUNCS_size_t_max(1, strlen(argv[3])) + 1) * sizeof(char));
     if ((arg1 == NULL) || (arg2 == NULL))
        {
        printf("EQ\n%s\n%s\n", argv[2], argv[3]);
        exit(0);
        }
     strcpy(arg1, argv[2]);
     strcpy(arg2, argv[3]);
     //Strip all of the non-digit trash out of the arguments.
     AUXFUNCS_remove_non_digits(arg1);
     AUXFUNCS_remove_non_digits(arg2);
     //Remove all leading zeros from both arguments.
     AUXFUNCS_remove_leading_zeros(arg1);
     AUXFUNCS_remove_leading_zeros(arg2);
     //If either argument is zero length, fill it in with 0.
     if (!strlen(arg1))
        strcpy(arg1, "0");
     if (!strlen(arg2))
        strcpy(arg2, "0");
     //If either argument exceeds 1000 digits, abort.
     if ((strlen(arg1)>1000) || (strlen(arg2) > 1000))
        {
        printf("EQ\n0\n0\n");
        return(0);
        }
     //If either argument is zero, abort.
     if (!strcmp(arg1, "0"))
        {
        printf("EP1B\n0\n0\n");
        return(0);
        }
     if (!strcmp(arg2, "0"))
        {
        printf("EP2B\n0\n0\n");
        return(0);
        }
     //Initialize all of the GMP variables.
     mpz_init(alg_a);
     mpz_init(alg_b);
     mpz_init(alg_adivb);
     mpz_init(alg_amodb);
     //Assign a and b to initial values.
     mpz_set_str(alg_a, arg1, 10);
     mpz_set_str(alg_b, arg2, 10);
     //We assume at this point that we will be successful.  Output
     //the header stuff.
     printf("S\n");
     mpz_out_str(stdout, 10, alg_a);
     printf("\n");
     mpz_out_str(stdout, 10, alg_b);
     printf("\n");
     //We require as an initial condition that a >= b.  Make
     //that happen.
     if (mpz_cmp(alg_a, alg_b) < 0)
        {
        mpz_swap(alg_a, alg_b);
        }
     //To make the algorithm cleaner, we preload for the first
     //assignment.
     mpz_set(alg_amodb, alg_b);
     mpz_set(alg_b,     alg_a);
     //Now begin the algorithm proper.
     round = 0;
     do
        {
        //We are at next round.
        round++;
        //Values for this round inherited from the last one.
        mpz_set(alg_a, alg_b);
        mpz_set(alg_b, alg_amodb);
        //Calculate the quotient and remainder.
        mpz_fdiv_qr(alg_adivb, alg_amodb, alg_a, alg_b);
        //Output all the data from the round.
        printf("%d\n", round);
        mpz_out_str(stdout, 10, alg_a);
        printf("\n");
        mpz_out_str(stdout, 10, alg_b);
        printf("\n");
        mpz_out_str(stdout, 10, alg_adivb);
        printf("\n");
        mpz_out_str(stdout, 10, alg_amodb);
        printf("\n");
        }
     while((round < 2000) && (mpz_sgn(alg_amodb) > 0));
     //The GCD canonically will be the last non-zero remainder.
     mpz_out_str(stdout, 10, alg_b);
     printf("\n");
     //Finally, we output the trailing "S".
     printf("S\n");
     return(0);
     }
  //********************************************************************************
  // $Log: subfunc_gcd.c,v $
  // Revision 1.5  2003/07/01 03:46:58  dtashley
  // Edits towards working continued fraction best rational approximation
  // functionality.
  //
  // Revision 1.4  2003/04/17 20:02:05  dtashley
  // License text for the GPL added.  All source files are now under the GPL,
  // after some discussion on the GMP list.
  //
  // Revision 1.3  2003/04/14 23:27:01  dtashley
  // Subfunction GMP_PROB_PRIME finished.
  //
  // Revision 1.2  2003/04/14 02:55:25  dtashley
  // Final edits on GCD.
  //
  // Revision 1.1  2003/04/13 23:46:06  dtashley
  // Initial checkin.
  //********************************************************************************
  // End of SUBFUNC_GCD.C.
  //********************************************************************************

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