log1p

• namespace: Rindow\NeuralNetworks\Gradient\Func
• classname: Log1p

Differentiable log(1+x) function.

Computes the natural logarithm of one plus the input accurately for small values.

Methods

log1p

$g->log1p(
    Variable|NDArray $x
) : Variable

Create and execute the function in the builder method

Arguments

• x: The argument is Variable or NDArray. Implicitly create Variable for NDArray.

use Rindow\Math\Matrix\MatrixOperator;
use Rindow\NeuralNetworks\Builder\NeuralNetworks;
$mo = new MatrixOperator();
$nn = new NeuralNetworks($mo);
$g = $nn->gradient();
$a = $g->Variable([0,1]);
$c = $nn->with($tape=$g->GradientTape(),function() use ($g,$a) {
    return $g->log1p($a);
});
$da = $tape->gradient($c,$a);
echo $mo->toString($c,'%6.3f')."\n";
echo $mo->toString($da,'%6.3f')."\n";

# [ 0.000, 0.693]
# [ 1.000, 0.500]