int xtract_highest_value(const double *data, const int N, const void *argv, double *result)
{
int n = N;
*result = data[--n];
while(n--)
*result = XTRACT_MAX(*result, data[n]);
return XTRACT_SUCCESS;
}
int xtract_peak_spectrum(const double *data, const int N, const void *argv, double *result)
{
double threshold, max, y, y2, y3, p, q, *input = NULL;
size_t bytes;
int n = N, rv = XTRACT_SUCCESS;
threshold = max = y = y2 = y3 = p = q = 0.0;
if(argv != NULL)
{
q = ((double *)argv)[0];
threshold = ((double *)argv)[1];
}
else
rv = XTRACT_BAD_ARGV;
if(threshold < 0 || threshold > 100)
{
threshold = 0;
rv = XTRACT_BAD_ARGV;
}
XTRACT_CHECK_q;
input = (double *)calloc(N, sizeof(double));
bytes = N * sizeof(double);
if(input != NULL)
input = memcpy(input, data, bytes);
else
return XTRACT_MALLOC_FAILED;
while(n--)
max = XTRACT_MAX(max, input[n]);
threshold *= .01 * max;
result[0] = 0;
result[N] = 0;
for(n = 1; n < N; n++)
{
if(input[n] >= threshold)
{
if(input[n] > input[n - 1] && n + 1 < N && input[n] > input[n + 1])
{
result[N + n] = q * (n + (p = .5 * ((y = input[n-1]) -
(y3 = input[n+1])) / (input[n - 1] - 2 *
(y2 = input[n]) + input[n + 1])));
result[n] = y2 - .25 * (y - y3) * p;
}
else
{
result[n] = 0;
result[N + n] = 0;
}
}
else
{
result[n] = 0;
result[N + n] = 0;
}
}
free(input);
return (rv ? rv : XTRACT_SUCCESS);
}
