coding midlet for TF

[starrynte]

I finished the "powering algorithm" (described on the math page of GIMPS) , any suggestions for improvements in speed/size?

public boolean testFactor(int expo,int factor){
    String n=Integer.toBinaryString(expo); //the binary representation
    long temp=1;
    do{
        temp*=temp; //square
        temp<<=Integer.parseInt(n.substring(0,1)); //if the top bit is 1, multiply by 2
        temp%=factor; //mod <the test factor>
    }while((n=n.substring(1)).length()>0); //remove the top bit, and continue if there is still more to do
    return (temp==1)?true:false; //if the final result is 1, then the test factor was a factor!
}

(Still trying to work out the GUI and sieving)

[R. Gerbicz]

Originally Posted by starrynte

I finished the "powering algorithm" (described on the math page of GIMPS) , any suggestions for improvements in speed/size?

Use sliding windows. (In gmp it is already implemented, see it's source.)