Subj : Re: Dartmouth BASIC to C
To   : comp.programming
From : Marlene Stebbins
Date : Mon Aug 08 2005 10:30 pm

John Smith wrote:
> Having nothing better to do on a Saturday morning, I was looking at 
> Kemeny & Kurtz's 1964 manual for BASIC:
> 
> http://www.bitsavers.org/pdf/dartmouth/BASIC_Oct64.pdf
> 
> Below is a C port of the first example program given in the manual. Can 
> it be improved while preserving, as much as possible, the structure of 
> the original BASIC program?

How about this?

#include <stdio.h>
#include <stdlib.h>
void READ(double *var);

double DATA[] = {1.0, 2.0, 4.0, 2.0,
                 -7.0, 5.0, 1.0, 3.0,
                  4.0, -7.0};

int main(void)
{
     int sys;
     double A1, A2, A3, A4;
     double D, X1, X2, B1, B2;

     READ(&A1);
     READ(&A2);
     READ(&A3);
     READ(&A4);

     D = A1 * A4 - A3 * A2;
     if(D == 0.0)
     {
         printf("no unique solution\n");
         exit(EXIT_SUCCESS); /* hope this makes Gerry Quinn happy :-)*/
     }

     for(sys = 0; sys < 3; sys++)
     {
         READ(&B1);
         READ(&B2);
         X1 = (B1 * A4 - B2 * A2) / D;
         X2 = (A1 * B2 - A3 * B1) / D;
         printf("%f %f\n", X1, X2);
     }

     return 0;
}

void READ(double *var)
{
     static int datum;
     *var = DATA[datum++];
     return;
}

.