double Denoise::gain_em(double Rprio, double Rpost, double alpha)
{
/* Ephraim-Malah classic noise suppression, from 1984 paper */
double gain = 0.886226925*sqrt(1.0/(1.0+Rpost)*(Rprio/(1.0+Rprio)));
gain *= hypergeom((1.0+Rpost)*(Rprio/(1.0+Rprio)));
return gain;
}
char twotail_exact(struct tw *m, double *cp, double *sp)
#define PR (*cp)
#define FT (*sp)
{
char k;
struct entry em;
double sec_prob, check, orig_p;
int orig_cross;
em=copy_entry(m);
if( !(em.x1 * em.x4 - em.x2 * em.x3) ) {
printf("exact fit -> det = 0\n");
*cp=1.;
*sp=0.5;
exactfit=1;
return 1;
}
/* probability of the original table */
if((PR=hypergeom(&em)) < 0.0) {
PR=FT=DMY;
return -1;
}
k=minx(&em);
orig_p=PR;
switch (k) { /* first tail */
case 1:
while( em.x1 && em.x4 ) {
--em.x1; /* decrement 11-22 diagonal */
--em.x4;
++em.x2;
++em.x3;
if((check=hypergeom(&em)) < 0.0) {
PR=FT=DMY;
return -1;
}
PR+=check;
}
break;
case 2:
while( em.x2 && em.x3 ) {
--em.x2; /* decrement 12-21 diagonal */
--em.x3;
++em.x1;
++em.x4;
if((check=hypergeom(&em)) < 0.0) {
PR=FT=DMY;
return -1;
}
PR+=check;
}
break;
}
#define X1 em.x1
#define X2 em.x2
#define X3 em.x3
#define X4 em.x4
/* second tail */
em=copy_entry(m);
orig_cross = ABS( X1*X4 - X2*X3 );
sec_prob=0.0;
switch (k) {
case 1:
while( em.x2 && em.x3 ) {
--em.x2; /* decrement 12-21 diagonal */
--em.x3;
++em.x1;
++em.x4;
if ( ABS( X1*X4 - X2*X3 ) < orig_cross ) continue;
if((check=hypergeom(&em)) < 0.0) {
PR=FT=DMY;
return -1;
}
if(check > orig_p) continue;
sec_prob+=check;
}
break;
case 2:
while( em.x1 && em.x4 ) {
--em.x1; /* decrement 11-22 diagonal */
--em.x4;
++em.x2;
++em.x3;
if ( ABS( X1*X4 - X2*X3 ) < orig_cross ) continue;
if((check=hypergeom(&em)) < 0.0) {
PR=FT=DMY;
return -1;
}
if(check > orig_p) continue;
sec_prob+=check;
}
break;
}
/* probabilities */
FT=PR; /* first tail (closest) */
PR+=sec_prob; /* both tails */
return 1;
#undef PR
#undef FT
#undef X1
#undef X2
#undef X3
#undef X4
}
