sigmoid和softmax函式的C++實現
阿新 • • 發佈:2019-02-03
float sigmoid(float x)
{
return (1 / (1 + exp(-x)));
}
float sigmoid_dy_dz(float x)
{
return (x * (1.0 - x));
}
float tanh_dy_dz(float x)
{
return (1.0 - x*x);
}
//對每一行進行softmax
void softmax(float *x, int row, int column)
{
for (int j = 0; j < row; ++j)
{
float max = 0.0;
float sum = 0.0;
for (int k = 0; k < column; ++k)
if (max < x[k + j*column])
max = x[k + j*column];
for (int k = 0; k < column; ++k)
{
x[k + j*column] = exp(x[k + j*column] - max); // prevent data overflow
sum += x[k + j*column];
}
for (int k = 0; k < column; ++k) x[k + j*column] /= sum;
}
} //row*column