help with generating random numbers between -1 and 1

[ILtech]

Math.random() returns a number in the interval [0, 1), right?

So, if I need to change the interval to (-1, 1), would I use do this...

xCoord = Math.random() * 2 - 1;

to change the range to be 2 (so it'd be [0, 2) then subtract one to shift it to (-1, 1)?

[Laharl]

This oughtta work, give it a shot.

[teek5449]

Don't forget that Math.random() returns a double between 0.0 and 1.0. in order to get the correct results you may need a conditional test.

Maybe something like (yes tertiary, my professor would kill me :) )

int number = Math.random() >= 0.5 ? 1 : -1;

[JosAH]

Math.random() returns a number in the interval [0, 1), right?

So, if I need to change the interval to (-1, 1), would I use do this...

xCoord = Math.random() * 2 - 1;

to change the range to be 2 (so it'd be [0, 2) then subtract one to shift it to (-1, 1)?

A small nitpick: if you multiply the range [0,1) by two you get the range [0,2);
after subtracting one you get the range [-1,1). Note the inclusion on the left
side and exclusion on the right side.

The solution is simple: while the original random value happens to be zero,
generate another random number.

kind regards,

Jos