matlab中反傅里叶变换出现错误

yiwy123

% Question (a) %
% compute and plot y(t) using convolution integral%
syms t;
syms w;
x = exp(-t) .* heaviside(t);
h = heaviside(t);
y1 = ( 1 - exp(-t) ) .* heaviside(t); % Compute using formula
subplot(2, 2, 1); ezplot(y1); title ' figure of y(t) = x(t) * h(t) ';
% compute and plot the inverse fourier transform using Y(jw) = H(jw)X(jw) %
X = fourier(x, t, w);
H = fourier(h, t, w);
Y1 = X .* H;
y2 = ifourier(Y1, t);
subplot(2, 2, 2); ezplot(y2); title ' figure of inverse fourier transform of X(jw)H(jw) ';
% Question (b) %
% plot the ideal low pass filter %
f = sin(t) ./ (pi * t);
ILPF = fourier(f, t, w);
subplot(2, 2, 3);
ezplot(abs(ILPF)); title ' magnitude of ILPF ';
% plot the inverse FT of X(jw) after filtering by ILPF %
Y2 = X .* ILPF;
y3 = ifourier(Y2, t);
subplot(2, 2, 4);
ezplot(y3); title ' output of x(t) after filtering by ILPF '




上面的代码不知道为什么不能画最后一个图，出现如下的错误
Error using char
Cell elements must be character arrays.

Error in ezplot (line 159)
                    fmsg = char(f);

Error in sym/ezplot (line 45)
   h = ezplot(char(f));

希望有心人能够解答，我已经百度了好几小时了，还是解决不了。谢谢

yiwy123

补充一下
f = sin(t) ./ (pi * t);如果按照我想的话，这个应该是理想低通滤波器吧？

yiwy123

顶一顶

yiwy123

看来这里的水平不咋的