lib/prime_number_bands.c


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// Prime Number Bands
//
// prime_number_bands
//
// Prime Number Bands
//
// 
//
// Inputs:    1
// Outputs:   3
// Constants: 1


#include <math.h>
#include "ts.h"

typedef struct {
    uint_t k;
} ts_prime_number_bands_params_t;

ts_parameter_t const ts_prime_number_bands_p = { .n_inputs = 1, .n_outputs = 3, .n_constants = 1, .params_size = sizeof(ts_prime_number_bands_params_t) };

uint_t ts_prime_number_bands_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? ((ts_prime_number_bands_params_t const *)c)->k - 1 : 0 );
}

int ts_prime_number_bands(
	fp_t * const *y, uint_t y_n,
	fp_t const * const *x, uint_t x_n,
	uint_t n, ts_constant_t const *c
)
{
	TS_PROLOGUE( ts_prime_number_bands_p );
	if ( !c ) return -1;
	uint_t k = ((ts_prime_number_bands_params_t const *)c)->k;
	if (k == 0 || n < k) return -1;

	for( uint_t i = k - 1; i < n; ++i )
	{
		fp_t sum = 0, sum2 = 0;
		for( uint_t j = 0; j < k; ++j )
		{
			fp_t v = x[0][i - k + 1 + j];
			sum += v;
			sum2 += v * v;
		}
		fp_t mean = sum / k;
		fp_t variance = sum2 / k - mean * mean;
		fp_t stddev = variance >= 0 ? sqrt( variance ) : 0;
		y[0][i] = mean;
		y[1][i] = mean + 2.0 * stddev;
		y[2][i] = mean - 2.0 * stddev;
	}
	return 0;
}