Integration of function containing if-test

[Francesco Potortì]

>I have a function nu(x) that is defined using an if-test. It has a 
>special value (0) at x = 0, and is defined in terms of an ordinary 
>function f(x) everywhere else. Therefore I have:
>
>function y = nu(x)
>	if (x == 0)
>		y = 0;
>	else
>		y = f(x);
>	endif
>endfunction
>
>When I pass it a 0 it returns a zero. But when I pass it a vector [0 1] 
>it doesn't work

If the function f works with vectors, then:

function y = nu(x)
  y = zeros (size (x));
  notzero = x(x != 0);
  y(notzero) = f (x(notzero));
endfunction

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