sigmoid.cpp

vector <float> sigmoid (const vector <float>& m1) {
    
    /*  Returns the value of the sigmoid function f(x) = 1/(1 + e^-x).
        Input: m1, a vector.
        Output: 1/(1 + e^-x) for every element of the input matrix m1.
    */
    
    const unsigned long VECTOR_SIZE = m1.size();
    vector <float> output (VECTOR_SIZE);
    
    
    for( unsigned i = 0; i != VECTOR_SIZE; ++i ) {
        output[ i ] = 1 / (1 + exp(-m1[ i ]));
    }
    
    return output;
}