从java循环总结产品

Question

I am having problems with summing up the products produced from my java loop.

public class ArtificialNeuron {

    public ArtificialNeuron(double[] weightings) {
        weights = weightings;
        inputs = new double[6];
        inputs[0] = 1;
    }

    public void setInput(int index, double newValue) {
        inputs[index] =  newValue;
    }

    public int activate(double threshold) {
        double x = 0;
        for(int i=0; i<inputs.length;i++)
            x = inputs[i]*weights[i];
        double sum = x+x+x+x+x+x;
        if(sum >= threshold) {
            return 1;
        } else {
            return -1;
        }
    }
}

I ran several Junit test and it always seem to fail on the if else statement. I believe it probably my summation method, but I don't know how I would sum up the products.

Answer 1

Based on your code, I think you wanted to add all of the products together. Instead, you are multiplying the last product by 6 (effectively). It's unclear why you have the temporary x , you can add each product to a default sum of 0 . Also, I think a test for sum < threshold is a little easier to read (likewise, always use braces with your loops - it's easier to read and reason about). Like,

public int activate(double threshold) {
    double sum = 0;
    for (int i = 0; i < inputs.length; i++) {
        sum += inputs[i] * weights[i]; // sum = sum + (inputs[i] * weights[i])
    }
    if (sum < threshold) {
        return -1;
    }
    return 1;
}