Error using ==> times Matrix dimensions must agree.

When I am executing this program, I got the error message

 ??? Error using ==>times Matrix dimensions must agree.

all i need to have is a signal that i will plot after multiplying the h vector and x input signal .

even with the same length , i couldn't find the problem

%generation de la reponse impultionnelle 

h=[ zeros(1 ,480) -436 -829 -2797 -4208 -17968 -11215 46150 34480 -10427 9049 -1309 -6320 390 -8191 -1751 -6051 -3796 -4055 -3948 -2557 -3372 -1808 -2259 -1300 -1098 -618 -340 -61 323 419 745 716 946 880 1014 976 1033 1091 1053 1042 794 831 899 716 390 313 304 304 73 -119 -109 -176 -359 -407 -512 -580 -704 -618 -685 -791 -772 -820 -839 -724 zeros(1 , 480)]

figure, plot(h)

axis([ 0 1024  -30000 50000]);

xlabel('amp');

ylabel('pnt');

title('reponse impulsionnelle ');

set(gcf, 'Color', [1 1 1])

%creation du signal far-end

[x,fs]=wavread('Alarm01.wav');

t=linspace(0,length(x)/fs,length(x)); % creation du vecteur temps

plot(t,x)

figure, plot(h)

Nfft=1024; %longueur du vecteur frequence

f=linspace(0,fs,Nfft);

G=abs(fft(x,Nfft));

figure ; plot(f(1:Nfft/2),G(1:Nfft/2),'g')

y=h'.*G.

plot(y)

Answer 1

[Roger Stafford]

Your vector t is a row vector, that is, presumably 1 by 1024 in size. If there is no complaint in plot(t,x), then x must also be 1 by 1024, which in turn means that G is 1 by 1024. However the vector h' is 1024 by 1, and that would produce an error in the multiplication y = h'.*G . You should insert size(h') and size(G) just before that multiplication to verify this.

[amira kadd]

thnks,actualy i used the G vector that is 1 by 1024 , i mean same as h .and the for loop to fixe the problem so that i store all the values from 1 to 1024 of my new vector befor the plot

 y=0;
for i=1:Nfft
Y(i)=h(i)'.*G(i)
end

 plot(Y);

[Roger Stafford]

You can accomplish the same thing with:

Y = h.*G;

since this way both arrays are 1 by 1024.

[amira kadd]

ah ok thanks , do you mean even without the transposed vector of h it works ?

[Roger Stafford]

Your h, as you have written it here, is a row vector 1-by-1024 in size. It is only h.*G that works, and h'.*G does NOT work, since G is also a row vector of the same size as h.