#include <stdio.h>
#include <stdlib.h>
#include <math.h>
typedef double (*func_t) (double);
typedef struct values_s{
double *arg;
double *funcval;
long size;
} values_t;
typedef enum boolean_e{
FALSE = 0,
TRUE = 1
} boolean_t;
double func1 (double x)
{
return 2*sin(x)-0.5;
}
double func2 (double x)
{
return 2*cos(x);
}
values_t *values_allocate(long size)
{
values_t *val=calloc(1,sizeof(values_t));
if(!val)
{
fprintf(stderr,"Allocate Error!");
return 0;
}
val->arg=calloc(size,sizeof(double));
val->funcval=calloc(size,sizeof(double));
if(!val->arg ||!val->funcval)
{
fprintf(stderr,"Allocate Error!");
free(val);
return 0;
}
val->size = size;
return val;
}
boolean_t values_insert(values_t *val,double arg,double value,long index)
{
boolean_t status=FALSE;
if(!val)
{
fprintf(stderr,"Nullpointer!");
return status;
}
if(index<0 || index >= val->size)
{
fprintf(stderr,"Index out of range!");
return status;
}
val->arg[index] = arg;
val->funcval[index] = value;
return status=TRUE;
}
boolean_t values_free(values_t *val)
{
boolean_t status=FALSE;
if(!val)
{
fprintf(stderr,"Nullpointer!");
return status;
}
free(val->arg);
free(val->funcval);
free(val);
return status=TRUE;
}
boolean_t values_print(values_t *val)
{
boolean_t status=FALSE;
long i;
if(!val)
{
fprintf(stderr, "Nullpointer.\n");
return status;
}
for(i=0;i<val->size;i++)
printf("%ld. %5g, %5g\n", i, val->arg[i], val->funcval[i]);
return status=TRUE;
}
double newton_step(double x0, func_t func, func_t derivate)
{
if(derivate(x0)==0)
{
fprintf(stderr, "Error: Division by Zero.\n");
return 0;
}
return x0-func(x0)/derivate(x0);
}
void values_store(values_t *val)
{
FILE *fp=fopen("C:\\users\\Patrick\\Dropbox\\3tes_Semester\\prog2\\Übung4\\newton.txt","w");
long i;
if(fp)
{
for(i=0;i<val->size;i++)
{
fprintf(fp,"%lf\t%lf\n",val->arg[i],val->funcval[i]);
}
}
else fprintf(stderr,"Fehler!");
fclose(fp);
}
void values_plot()
{
FILE *gnuplot = popen("C:\\Users\\Patrick\\Dropbox\\3tes_Semester\\prog2\\Übung4\\newton.txt -persist","w");
if (gnuplot)
{
fprintf(gnuplot, "set title 'P2-UE4: Newton'\n");
fprintf(gnuplot, "set style data lines\n");
fprintf(gnuplot, "cd 'C:\\Programme\\gnuplot\\bin'\n");
fprintf(gnuplot, "f(x)=2*sin(x)-0.5\n");
fprintf(gnuplot, "plot [2.8:3.1] \"p2ue4_newton.txt\" using 1:2 with steps, f(x)\n");
}
pclose(gnuplot);
}
void newton_iter(double x0, long steps, double precision, func_t func, func_t derivate)
{
long i=0;
double xn=0;
values_t *val=values_allocate(steps);
values_insert(val,x0,func(x0),0);
for(i=0;i<steps && (fabs(val->funcval[i])>precision);i++)
{
xn=newton_step(val->arg[i],func,derivate);
values_insert(val,xn,func(xn),i+1);
}
values_print(val);
values_store(val);
values_plot();
values_free(val);
}
int main()
{
newton_iter(3,10,0.0001,func1,func2);
return 0;
}
