Mathematicians required!

Hey guys, I did some curve fitting for something I am doing, and I need to get this working, although I am not familiar enough with the "Math" class, because plugins don't normally require a lot of math, lol. So I was wondering if anyone could tell me how to get the exponent working, and also if I am doing anything wrong for curve fitting...

Code:

    protected double amountVariable() {
        double x = game.getPlayers().size() * 1.5;
        double a = 5.150202692369555E-4;
        double b = 0.009694737048487135;
        double c = 2.0740001246685478;
        double d = 1.5771190606123884;
        return d + (c * x) + (b * x)^2 - (a * x)^3;
    }

 

Math.pow(double base, double exponent)

EDIT: Although it might be faster to just use *, at least for ^2. Like this:

Code:java

double bx = b * x;
double ax = a * x;
return d + c * x + bx * bx - ax * ax * ax;

 

ahh okay, thanks. That makes complete sense!

 

Yeeah, the ^ sign in Java is a bitwise XOR operator and nothing to do with exponents, I've made the same mistake before

 

Surprisingly, it's faster to do exponents on a bitwise level than multiplications, so
in this case, Java's Math.pow would be the faster method. But unless you care about a one
nanosecond difference... or are slightly insane, you should just go with the one that is the
most easy for you to understand. (I would learn the Math class's primary utility methods though
as they are extremely necessary for doing... well... like... everything)

 

All java math ops are pretty cheap except for the trig ones (which can be done better with a lookup table) and the horrendous square root.

 

They don't use a lookup table :O oh dear... why java why! :/

Also, never looked at their Sqrt implementation, what's so terrible about it?

 

This is their implementation of sin. It is in C.
This is their implementation of pow. It might call this. It is also in C.

The documentation doesn't explicitly say what their implementation of sqrt is. It probably depends on the JVM. It might be this, if it is software.
There is this comment: "Note that hardware sqrt instructions frequently can be directly used by JITs and should be much faster than doing Math.sqrt in software."