68 lines
995 B
C
68 lines
995 B
C
#include "solve.h"
|
|
#include "status.h"
|
|
|
|
#include <math.h>
|
|
#include <float.h>
|
|
#include <stdbool.h>
|
|
#include <stdint.h>
|
|
#include <string.h>
|
|
|
|
int t9_solve (
|
|
double (*f) (double),
|
|
double a, double b,
|
|
double eps, int m, double *x
|
|
) {
|
|
int it = 0;
|
|
double c = DBL_MAX, y, y_a = f(a), y_b = f(b);
|
|
|
|
if (fabs(y_a) - eps < DBL_EPSILON)
|
|
{
|
|
*x = a;
|
|
return SUCCESS;
|
|
} if (fabs(y_b) - eps < DBL_EPSILON)
|
|
{
|
|
*x = b;
|
|
return SUCCESS;
|
|
}
|
|
|
|
if (sgn_a == sgn_b)
|
|
{
|
|
*x = DBL_MAX;
|
|
return MORE_ONE_ROOT;
|
|
}
|
|
|
|
for (it = 0; it < m; ++it)
|
|
{
|
|
c = (a + b) * 0.5;
|
|
y = f(c);
|
|
|
|
memcpy(&bits, &y, sizeof(bits));
|
|
sgn_c = (bits >> 63) & 1;
|
|
|
|
if (fabs(y) - eps < DBL_EPSILON)
|
|
{
|
|
ret = SUCCESS;
|
|
break;
|
|
} else if ((fabs(c - a) < DBL_EPSILON) || (fabs(c - b) < DBL_EPSILON))
|
|
{
|
|
ret = HIGH_ERROR;
|
|
break;
|
|
} else if (sgn_c == sgn_a)
|
|
{
|
|
a = c;
|
|
y_a = y;
|
|
} else if (sgn_c == sgn_b)
|
|
{
|
|
b = c;
|
|
y_b = y;
|
|
}
|
|
}
|
|
|
|
if (it >= m)
|
|
ret = RUN_TIME;
|
|
|
|
*x = c;
|
|
|
|
return ret;
|
|
}
|
|
|