Error using .* Matrix dimensions must agree.

M = 25;
alpha = (M-1)/2;
n = 0:M-1;
hd = (2/pi)*((sin((pi/2)*(n-alpha)).^2)./(n-alpha));
hd(alpha+1)=0;
w_han = '(hann(M))';
h = hd .* w_han;       %%%here is the error

[KALYAN ACHARJYA]

Array multiplication between numeric array and character array??

> whos hd
  Name      Size            Bytes  Class     Attributes
  hd        1x25              200  double              
>> whos w_han
  Name       Size            Bytes  Class    Attributes
  w_han      1x9                18  char      

Aim?

w_han??

[muhammad nur adri nawi]

%%% problem this code cannot run
M = 25;
alpha = (M-1)/2;
n = 0:M-1;
hd = (2/pi)*((sin((pi/2)*(n-alpha)).^2)./(n-alpha));
hd(alpha+1)=0;
w_han = '(hann(M))';
h = hd .* w_han.';
[Hr,w,c,L] = Hr_Type3(h);
subplot(2,2,1); stem(n,hd); title('Ideal Impulse Response')
axis([-1 M -1.2 1.2]); xlabel('n'); ylabel('hd(n)')

subplot(2,2,2);
stem(n,w_han);
title('Hann Window');
axis([-1 M 0 1.2]); xlabel ' n '); ylabel('w(n)')
subplot(2,2,3); stem(n,h);title('Actual Impulse Response')
axis([-1 M -1.2 1.2]); xlabel('n'); ylabel('h(n)')
w = w'; Hr = Hr';
w = [-fliplr(w), w(2:501)]; Hr = [-fliplr(Hr), Hr(2:501)];
subplot(2,2,4);plot(w/pi,Hr); title('Amplitude Response');grid;
xlabel('frequency in pi units'); ylabel('Hr'); axis([-1 1 -1.1 1.1]);

Answer 1

[KALYAN ACHARJYA]

In this case hd is numeric array with size 25

whos hd
  Name      Size            Bytes  Class     Attributes
  hd        1x25              200  double   

Whereas w_han is character array with size 9

>> whos w_han
  Name       Size            Bytes  Class    Attributes
  w_han      1x9                18  char  

Once you try to multiply between the numeric array and the character array, you supose to get an error as follows

Error using  .* 
Matrix dimensions must agree.

If somehow you increase the size of w_han to 25, then no error can occur. Are you really looking for that? In such case it get multiplied with ASCII code of respective character, see the example

>> a='m'
a =
    'm'
>> b=5;
>> c=b.*a
c =
   545

Here b is multiplied with ASCII code of m, which is 109, as

>> 5*109
ans =
   545

I just want to mention this point, so that you can get the idea, if somehow an error cannot occur, it can happen in such a case.