Floating point complex modulus
Calculating a floating point complex modulus isn't quite trivial. The naive method may encounter overflow, underflow, or loss of precision due to the intermediate floating point results. A simple remedy[1] is:

require('complex-modulus')( a, b )Calculates |a + ib| and returns a number
var cmod = require('complex-modulus');
var result = cmod( 3, 4 );
// result = 5
[1] Press, William H. Numerical Recipes 3rd Edition: The Art of Scientific Computing. Cambridge University Press, 2007.
(c) 2015 Ricky Reusser. MIT License