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  • ¶
  • ¶

    Useful mathematical functions which should be part of the JavaScript Math object.

  • ¶

    Compute conversion from degrees to radians.

    Math.radians = (degrees) ->
  degrees * Math.PI / 180
  • ¶

    Compute conversion from radians to degrees.

    Math.degrees = (radians) ->
  radians * 180 / Math.PI
  • ¶

    Obtain the sign of the given number.

    Math.sign = (num) ->
  if num
    if num < 0
      return -1
    else
      return 1
  else
    return 0
  • ¶

    Compute conversion from degrees to radians.

    Math.factorial = (x) ->
  if x < 2
    return 1
  else
    return Math.factorial(x-1)*x
  • ¶

    Compute the base-10 logarithm of x.

    Math.log10 = (x) ->
  Math.log(x) / Math.LN10
  • ¶

    Compute the error function of x.

    • http://en.wikipedia.org/wiki/Error_function
    • https://github.com/ghewgill/picomath
    Math.erf = (x) ->
  • ¶

    Constants

      a1 = 0.254829592
  a2 = -0.284496736
  a3 = 1.421413741
  a4 = -1.453152027
  a5 = 1.061405429
  p = 0.3275911
  • ¶

    Save the sign of x

      sign = 1
  sign = -1  if x < 0
  x = Math.abs(x)
  • ¶

    Formula 7.1.26 from:

    • Abramowitz, M. and Stegun, I. A. (Eds.). “Error Function and Fresnel Integrals.” Ch. 7 in Handbook of Mathematical Functions with Formulas, Graphs, and Mathematical Tables, 9th printing. New York: Dover, pp. 297-309, 1972.
      t = 1.0 / (1.0 + p * x)
  y = 1.0 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * Math.exp(-x * x)
  sign * y