/* ---------------------------------- */
/* save as c18b.c                    */
/* ---------------------------------- */
#include "x_hfile.h"
#include      "fb.h"
/* ---------------------------------- */
int main(void)
{
double a = -1;
double b =  3;

double   x1 = -1.;
double   y1 =  2.;

double   x2 =  3;
double   y2 =  1.;

int      n =  2*50;
double   m = 0;
/* ---------------------------------- */

 clrscrn();
 printf(" Let  F(x,y) = M(x,y)n + N(x,y)h \n\n\n");
 printf(" Be continuous on an open connected region D,\n");
 printf(" And let C be a piecewise-smooth curve  in D\n");
 printf(" With endpoints A(x1,y1) and B(x2,y2).\n\n\n");
 printf(" If F(x,y) = grad f(x,y) then \n\n\n");
 printf("    (                          ((x2,y2)              (x2,y2)\n");
 printf(" int( M(x,y)dx + N(x,y)dy = int(       F.dr = [f(x,y)]\n");
 printf("    (c                         ((x1,y1)              (x1,y1)\n");
 printf(" \n");
 stop();

/* ---------------------------------- */
 clrscrn();
 printf(" Let  F(x,y) = %si + %sj       \n\n",Meq,Neq);
 printf(" and has  C parametrization :\n\n");
 printf(" x = %s;     y = %s;       %.1f < t =< %.1f \n\n\n",
          geq, heq, a, b);
 printf(" Let  f(x,y) = %s              \n\n\n",feq);
 printf(" Verify if F(x,y) = grad f(x,y)\n\n\n");

 m  =lineintegral_dx(
              M,
              g,h,
              a,b,n,
              H);

 m  +=lineintegral_dy(
              N,
              g,h,
              a,b,n,
              H);
              
 printf("  then \n\n");
 printf("        (b\n");
 printf("     int(        F.dr  =  %+.3f\n",  m);
 printf("        (a\n\n\n");
 printf("  f(x2,y2) - f(x1,y1)  = %+.3f\n", f(x2,y2) - f(x1,y1));
 stop();

 return 0;
}
/* ---------------------------------- */
/* ---------------------------------- */