Multiply by the power of 2 in java?

Stellios · 3 May 2007 at 10:16

I need to multiply by the power of 1^2, 2^2, 3^3 etc etc

Im crap at maths, is it possible for anyone to tell me how to code this in java pretty please?

Cheers

Stellios · 3 May 2007 at 10:32

Hmmm, think ive jsut found a solution.

Quick Q, is 2*=2 the equivalent of 2^2? Ive just tried it and it works.

elkdanger · 3 May 2007 at 10:42

Stellios said:
Hmmm, think ive jsut found a solution.

Quick Q, is 2*=2 the equivalent of 2^2? Ive just tried it and it works.

I'm not entirely sure what it is in java, although it might be a function such as pow() or it could even actually be 2^2 (^ is the power operator in C#, might be the same in Java).

However, just to correct you on your above question, 2*=2 is equivalent to 2 = 2 * 2 (or a = a * b). It just so happens that in your example 2*=2 and 2 raised to the power of 2 produce the same answer.

daz · 3 May 2007 at 10:44

2^0 = 1
2^1 = 2 = 2
2^2 = 2*2 = 4
2^3 = 2*2*2 = 8
2^4 = 2*2*2*2 = 16

Etc.

You can either do it recursively (using the base case as 2^0 = 1) - probably not as good performance wise (but it looks neat in programming terms), or use an iterative method.

elkdanger said:
I'm not entirely sure what it is in java, although it might be a function such as pow() or it could even actually be 2^2 (^ is the power operator in C#, might be the same in Java).

Using that might be quite a bit slower.

Stellios · 3 May 2007 at 10:44

Ahhhhhhhhhh, thanks a lot for that mate. Wasnt sure what it done, now all is clear

daz · 3 May 2007 at 10:47

Stellios said:
I need to multiply by the power of 1^2, 2^2, 3^3 etc etc

If you're just squaring something (x^2) then you multiply it by itself. (x * x)

If you're cubing something (x^3), then you multiply it by itself twice (x * x * x)

Dj_Jestar · 3 May 2007 at 10:48

Math.pow(double a, double b)

Stellios · 3 May 2007 at 12:22

Dj_Jestar said:
Math.pow(double a, double b)

Bam, spot on what im after

Thanks a lot mate

Inquisitor · 3 May 2007 at 12:28

elkdanger said:
or it could even actually be 2^2 (^ is the power operator in C#, might be the same in Java).

No it's not :/

^ is the XOR (exclusive OR) operator in C# and Java.

elkdanger · 3 May 2007 at 12:41

Inquisitor said:
No it's not :/

^ is the XOR (exclusive OR) operator in C# and Java.

You're right, I stand corrected.

Visage · 3 May 2007 at 13:36

elkdanger said:
You're right, I stand corrected.

...said the man in the orthopedic shoes.

Buttons · 3 May 2007 at 15:58

Bitwise left shifting is more efficient, google it