Scilab should have a function for calculating argument (angle) for a complex number

Reported by Nikolay Strelkov

BUG DESCRIPTION:
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Scilab 5.5.0 do not have a function for calculating argument (angle) for a complex number.
Please add built-in function for such simple task.

The function may look as follows:
  function a = arg (z)
    a = atan(imag(z), real(z));
  endfunction
or 
  function a = angle (z)
    a = atan(imag(z), real(z));
  endfunction


ERROR LOG:
----------
none

HOW TO REPRODUCE THE BUG:
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1. Define complex number
2. Try to calculate its argument (angle) - you should use atan manually instead of using built-in function.


OTHER INFORMATION:
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Other mathematical programs have such function (for example, Octave, FreeMAT and MATLAB).