Question

I am using Math.PI in my example, so it is a double. It is a simple code but there is a bit I am not sure how to do:

I want the code to calculate the fundamental period X of a sin or cos function with a multiplier value a given by the user. The n value is initialized at n=1 and is an integer value.

If the result of (2 * pi * n)/a = X is lower than pi then n should increment, and it should keep going until that number is a multiple of pi, then print the result.

Just to clarify: a is a multiplier of x which goes in the function sin or cos like this:

cos(ax)

sin(ax)

The bit I am having the trouble with is working out whether the number is a multiple of pi (provided it’s already greater than pi, that is).

This is about as far as I got and it’s incomplete.

 public void printSinusoidalPeriod(double multiplier /* this would be `a` */){

    double pi=Math.PI;

    double p = (2 * pi * (double) n) / multiplier;

    while(p<pi){

        if(n%pi==0){

            n=n+1;
            System.out.println(n);
                            p = (2 * pi * (double) n) / multiplier;
        }
    }
    p= (double)Math.round(p * 100) / 100;


    System.out.println("period of function is = " + p + " and n = " + n);
}

It seems like it’s not going into the if statement and getting caught in the while loop

Answer 1

Ok here’s how I did it in the end, with the help of the suggestions here.

public void printSinusoidalPeriod(double a){

    double pi=Math.PI;
    double p=m*pi;

    while(n<a/2){

        if((double)Math.round((n*pi)%pi)!=0.01){

            n=n+1;

            m = (int) Math.round(((2 * (double) n) / a));
            p= (double)Math.round(m * pi * 100) / 100;
            p=p*n;

        }
    }
    System.out.println("period of function is = " + p + " and n = " + n);
    System.out.println("Check: p/n = " + p/n);
}

Please let me know if you can spot any problems with the logic. I have not gone through many possibities yet, but the ones I did, looked okay to me.