Practical Neural Network Recipies in C++

394

Chapter 21

threshold. The direct_crit subroutine divides these counts by the

number of samples to get the error probability, then multiplies by the

prior probability times the misclassification cost, summing to get the

total cost.

static int count (

int n ,

double *array ,

double value

)

{

int lo, mid, hi ;

if (value > array[n-1])

return 0 ;

if (value <= array[0])

return n ;

lo = 0;

hi = n-1 ;

for (;;) {

mid = (lo + hi) / 2 ;

if (mid == lo)

return n - hi ;

if (array[mid] < value)

lo = mid ;

else

hi = mid ;

}

}

double direct_crit (

int ηθ ,

int

n1

,

double *s0 ,

double *s1 ,

double wtO ,

double wt1 ,

double thresh

)

// At all times we kee ...