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javascriptmathscale

convert decimals into negatives?

I'm scaling an image in css with transforms.

The scale goes from 0 to whatever, with 0 through 1 being smaller than the image.

I need to get the scale into negatives, so that 0 is the same size as the original, 1 is double the size, and -1 is half the size.

I have vars:

var cssScale, factorScale;

How to get cssScale into factorScale and vice versa?

Thanks.

Solution

  • Seems like you want 2-to-the-power-of-n:

    cssScale= Math.pow(2, factorScale);

    To get back the other way would be log-base-2, which you'd have to implement using log-base-E:

    factorScale= Math.log(cssScale)/Math.LN2;