Focal loss fixed

AlexeyAB

2018-04-18 eccfccdaf795d7c4d0cff1e884ebd62a8ca4ab7c

Focal loss fixed

 src/region_layer.c

@@ -136,8 +136,9 @@

            int ti = index + class_id;
            float pt = output[ti] + 0.000000000000001F;
            //float grad = -(1 - pt) * (2 * pt*logf(pt) + pt - 1);  // http://blog.csdn.net/linmingan/article/details/77885832	
            float grad = (1 - pt) * (2 * pt*logf(pt) + pt - 1);     // https://github.com/unsky/focal-loss
            // http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiItKDEteCkqKDIqeCpsb2coeCkreC0xKSIsImNvbG9yIjoiIzAwMDAwMCJ9LHsidHlwZSI6MTAwMH1d
            float grad = -(1 - pt) * (2 * pt*logf(pt) + pt - 1);    // http://blog.csdn.net/linmingan/article/details/77885832	
            //float grad = (1 - pt) * (2 * pt*logf(pt) + pt - 1);   // https://github.com/unsky/focal-loss

            for (n = 0; n < classes; ++n) {
                delta[index + n] = scale * (((n == class_id) ? 1 : 0) - output[index + n]);