/* test
* tests a zero finder (z) for a function (f), using message msg.
* tests the function on the interval [a,b].
* modified from vzeroin.c, a test for Brent's zeroin function (from netlib)
*/
double test(double a, double b, double (*z)(double a, double b,
double(*f)(double x), double t), double (*f)(double x), char *msg) {
double root;
counter = 0;
printf("\nFor function %s\nin [%g,%g] root is\t%.9e\n",msg,a,b,
(root=zeroin(a,b,f,0.0)) );
printf("No. of iterations\t\t%ld\n", counter);
printf("Function value at the root found\t%.4e\n", (*f)(root));
return root;
}
void binom_bayes(int *x,
int *n,
double *a,
double *b,
double *alpha,
double *lcl,
double* ucl,
int *len,
int *maxit,
double *tol,
int *error) {
int i, j, first, down;
double lcl_x, ucl_x, lcl_y, ucl_y;
double y1, y2, y3;
double px1, px2, sig;
double mode, xx;
double x1, x2;
double lx1, lx2, ux1, ux2;
double p[3];
for(j = 0; j < len[0]; j++) {
lcl_x = lcl[j];
ucl_x = ucl[j];
lcl_y = dbeta(lcl_x, a[j], b[j], NCP);
ucl_y = dbeta(ucl_x, a[j], b[j], NCP);
y3 = fmax(lcl_y, ucl_y);
y1 = 0;
mode = (a[j] - 1)/(a[j] + b[j] - 2);
first = (lcl_y < ucl_y ? 0 : 1);
x1 = first ? mode : 0;
x2 = first ? 1 : mode;
p[0] = y3;
p[1] = a[j];
p[2] = b[j];
xx = zeroin(dbeta_shift, x1, x2, p, tol[0], maxit[0]);
if(first) {
ucl_x = xx;
} else {
lcl_x = xx;
}
px1 = pbeta(lcl_x, a[j], b[j], LOWER_TAIL, LOG_P);
px2 = pbeta(ucl_x, a[j], b[j], UPPER_TAIL, LOG_P);
sig = px1 + px2;
down = 0;
i = 0;
while(fabs(sig - 2 * alpha[j]) > tol[0] && i < maxit[0]) {
y2 = (y1 + y3) * 0.5;
if(down) {
if(dbeta(lcl_x, a[j], b[j], 0) < y2)
lcl_x = mode;
lx1 = 0;
lx2 = lcl_x;
if(dbeta(ucl_x, a[j], b[j], 0) < y2)
ucl_x = mode;
ux1 = ucl_x;
ux2 = 1;
} else {
if(dbeta(lcl_x, a[j], b[j], 0) > y2)
lcl_x = 0;
lx1 = lcl_x;
lx2 = mode;
if(dbeta(ucl_x, a[j], b[j], 0) > y2)
ucl_x = 1;
ux1 = mode;
ux2 = ucl_x;
}
p[0] = y2;
lcl_x = zeroin(dbeta_shift, lx1, lx2, p, tol[0], maxit[0]);
ucl_x = zeroin(dbeta_shift, ux1, ux2, p, tol[0], maxit[0]);
px1 = pbeta(lcl_x, a[j], b[j], LOWER_TAIL, LOG_P);
px2 = pbeta(ucl_x, a[j], b[j], UPPER_TAIL, LOG_P);
sig = px1 + px2;
if(sig > 2 * alpha[j]) {
down = 0;
y3 = y2;
} else {
down = 1;
y1 = y2;
}
i++;
}
error[j] = (i >= maxit[0] ? 1 : 0);
lcl[j] = lcl_x;
ucl[j] = ucl_x;
}
}
