lib/softplus.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

// Softplus
//
// softplus - Softplus activation
//
// y[t] = log( 1 + exp( x[t] ) )
//
// X_n - 1
// Y_n - 1
// C_n - 0


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


ts_parameter_t const ts_softplus_p = { .n_inputs = 1, .n_outputs = 1, .n_constants = 0, .params_size = 0 };


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

int ts_softplus(
	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_softplus_p );
	(void)c;
	for( uint_t i = 0; i < n; ++i )
	{
		fp_t xi = x[0][i];
		if ( xi > 20 )
			y[0][i] = xi;
		else if ( xi < -37 )
			y[0][i] = exp( xi );
		else
			y[0][i] = log( 1 + exp( xi ) );
	}
	return 0;
}