倍频程变量定义错误

Question

I'm trying to generate Blackman-Harris window coefficients in Octave. I have declared a function in a .m file like so:

function result = BlackmanHarris(window_size)
  a0 = 0.35875
  a1 = 0.48829
  a2 = 0.14128
  a3 = 0.01168
  result = [0:window_size - 1];

  if(nargin != 1)
    print_usage("BlackmanHarris(int window_size)");
  endif

  if(isinteger(window_size))
    for n = 0:window_size - 1
      result(n) = a0 - (a1 * cos((2 * pi * n)/(window_size - 1))) + (a2 * cos((4 * pi * n)/(window_size - 1))) - (a3 * cos((6 * pi * n)/(window_size - 1)));
    endfor
  else
    error("BlackmanHarris: Expecting integer argument.");
  endif
endfunction

When I attempt to run this, I get the error:

>> window = BlackmanHarris(window_size);
error: 'a0' undefined near line 15 column 16
error: called from
    BlackmanHarris at line 15 column 14

I have tried declaring the variables as 'global' and 'persistent', nether of which solve this issue. I'm sure I'm just doing something slightly wrong, but Google has yielded little help on this.

Thanks in advance.

Answer 1

As @Sardar_Usama said, I was attempting to access element 0 of the result array, which of course will not work.

Changing that to n+1 fixed the issue.