Matlab - Interferencia en gráfica al introducir una línea de código

v_sis = machethomson(transpose(a_sis'),1/dt,.1,1);

d_sis = machethomson(transpose(a_sis'),1/dt,.1,2);

function [xint] = machethomson(x,fs,fc,order)

%MACHETHOMSON Frequency domain integration with ideal low pass filtering

%MACHETHOMSON(x, fs, fc, order)

%   x:      data. Matrix with rows of data.

%   fs:     sampling frequency in Hz.

%   fc:     lowpass frequency cutoff, 0 <= fc < 0.5 fs

%           (Default value: 0)

%   order:  order or number of times to be integrated

%           (Default value: 1)

%

%   Peter Thomson

%   23 March 2011

error(nargchk(2,4,nargin))

if nargin == 2, fc = 0; order = 1; end

if nargin == 3, order = 1; if fc >= 0.5*fs, error('fc must be less than 0.5 fs'), end, end

[a,b]=size(x);

if a > b, x=x';n=a;d=b; else n=b;d=a; end  %% make rows of data

xf=fft(x');                             %% fourier transform of data

xf=xf';

w=2*pi.*fs*(n-1)/n.*linspace(0,1,n);    %% full frequency vector

ind=find(w>=fc*2*pi,1,'first');         %% find cutoff frequency index

w=w(1:ceil((n+1)/2)); xf=xf(:,1:ceil((n+1)/2));   %% reduced vectors

%% Filter frequency vector such that operations are carried out for each

%% row and values below cutoff frequency made very large

wv=ones(d,1)*[1e99*ones(1,ind) w(ind+1:end)];

xintuf=(1./(-1i.*wv).^order).*xf;       %% integrate each term

plot(abs(xintuf))

if rem(n,2)==0                          %%depending on odd/even number of points

    xintuf=[xintuf fliplr(conj(xintuf(:,2:end-1)))];

else

    xintuf=[xintuf fliplr(conj(xintuf(:,2:end)))];

end

 xint=detrend(real(ifft(xintuf')))';

 xint=  xint - xint(:,1);

end