# Axis/Slider Scale

Hi,

Currently I’m having an issue with the slider of my Logitech joystick. The range is from -1 to 1 and I need to convert it to be from 0 to 1 rather than -1 to 1. How would I go about doing this? I’m using the Logitech Extreme 3D Pro and the axis number is 3. I’m using Java but I figured this is a language-wide issue, hence the post here.

Thanks!

``````
(stick.get() + 1) / 2
``````

In my experience, I’ve found that the slider has been unreliable. So, just watch out buddy.

If you are interested, here’s the algebra to solve that kind of problem, for any input and output range, assuming you want a linear conversion from input to output:

Let x be the input and y be the output.

You want a linear conversion, so use the equation for a line:

y = mx + b

When x is -1 you want y to be 0:

0 = m(-1) + b …(Equation1)

When x is 1 you want y to be 1:

1 = m(1) + b …(Equation2)

You have 2 equations with two unknowns, so solve them.

1 = 2b …=>… b = (1/2)

Subtract Equation1 from Equation2:

1 = 2m …=>… m=(1/2)

So the conversion is y = (1/2)x + (1/2) = (x+1)/2

Thanks for that information and thanks for the great explanation, Ether. I hadn’t thought of it that way (as a linear equation pair) but that actually makes sense.

Thank you!

While I understand that the problem is solved, i’m still rather intrigued – why did you feel the need to do this; have default be 0.5, and have the joystick(s) serve as a throttle to that?