function B = fir2(N, F, M, varargin) //Produce an order N FIR filter with arbitrary frequency response M over frequency bands F, returning the N+1 filter coefficients in B. //Calling Sequence //B = fir2(N, F, M) //B = fir2(N, F, M, GRID_N) //B = fir1(N, F, M, GRID_N, RAMP_N) //B = fir1(N, F, M, GRID_N, RAMP_N, WINDOW) //Parameters //N: Integer //F, M: Vector //Description //Produce an order N FIR filter with arbitrary frequency response M over frequency bands F, returning the N+1 filter coefficients in B. The vector F specifies the frequency band edges of the filter response and M specifies the magnitude response at each frequency. // //The vector F must be nondecreasing over the range [0,1], and the first and last elements must be 0 and 1, respectively. A discontinuous jump in the frequency response can be specified by duplicating a band edge in F with different values in M. // //The resolution over which the frequency response is evaluated can be controlled with the GRID_N argument. The default is 512 or the next larger power of 2 greater than the filter length. // //The band transition width for discontinuities can be controlled with the RAMP_N argument. The default is GRID_N/25. Larger values will result in wider band transitions but better stopband rejection. // //An optional shaping WINDOW can be given as a vector with length N+1. If not specified, a Hamming window of length N+1 is used. //Examples // fir2 (10, [0, 0.5, 1], [1, 2, 3]) //ans = // -0.00130 0.00000 -0.01792 0.00000 -0.36968 2.00000 -0.36968 0.00000 -0.01792 0.00000 -0.00130 funcprot(0); rhs = argn(2); if(rhs<3 | rhs>6) error("Wrong number of input arguments."); end select(rhs) case 3 then B = callOctave("fir2", N, F, M); case 4 then B = callOctave("fir2", N, F, M, varargin(1)); case 5 then B = callOctave("fir2", N, F, M, varargin(1), varargin(2)); case 6 then B = callOctave("fir2", N, F, M, varargin(1), varargin(2), varargin(3)); end endfunction