// Power
//
// power - pow
//
// f( x ) = x^r
//
// X_n - 1
// Y_n - 1
// C_n - 1
//
// c[0] = r


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


typedef struct {
    fp_t r;
} ts_power_params_t;

ts_parameter_t const ts_power_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_power_params_t) };


uint_t ts_power_offset( ts_constant_t const *c )
{
	( void )c;
	return ( 0 );
}

int ts_power(
	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_power_p );
	if ( !c ) return -1;
	fp_t r = ((ts_power_params_t *)c)->r;

	for( uint_t i = 0; i < n; ++i )
	{
		fp_t base = x[0][i];
		if ( base > 0 )
		{
			y[0][i] = pow( base, r );
		}
		else if ( base < 0 )
		{
			fp_t intpart;
			if ( modf( r, &intpart ) == 0 )
			{
				fp_t result = pow( -base, r );
				long ip = (long)intpart;
				y[0][i] = (ip >= 0 && (ip & 1) != 0) ? -result : result;
			}
			else
			{
				y[0][i] = 0;
			}
		}
		else
		{
			if (r > 0.0) y[0][i] = 0.0;
			else if (r < 0.0) y[0][i] = INFINITY;
			else y[0][i] = 1.0;
		}
	}
	return 0;
}