Matrix dimensions must agree!!

Dear all,

I am preparing a matlab simulation to plot the output of an SMI adaptive beamformer algorithm, but i keep getting "matrix dimensions must agree" response, and i'm new to matlab and have not been able to fix this issue.

I am kindly asking for assistance.

Many thanks.

Here is the code:

N = 7;
l = 0:N-1;
fs = 12e6;
f = 1e6;
fi = 1e3;
SNR = 0;
INR = 10;
m = 8;
c = physconst('LightSpeed');
lambda = c/f;
d = lambda/2;
angles = -90:1:90; 
theta = ([-pi/2,pi/2]);
phi = ([-pi,pi]);
j= sqrt(-1);
noisePwr = 0.5; % noise power
Ps = noisePwr*SNR; % signal power
A = Ps*10^(SNR/20);
I = 10^(INR/20);
s = A*exp(j*2*pi*f/fs*l);
i = I*exp(j*2*pi*fi/fs*l);
n = sqrt(noisePwr/2)*randn(m,l)+j*randn(m,l); 
k = (2*pi)/lambda;
S = s';
a = exp(-j*2*pi*d*(0:m-1)'*sind(angles));%steering matrix
B = ctranspose(a);
input = a*S;
X = input + i + n;
r= (X*ctranspose(X))/N;
R = inv(r);
alpha = inv(B*R*a);
w = alpha*R*a;  % weight vector
W = ctranspose(w);
Y = W*X;
plot (Y)

[Stephen23]

Can you please tell us where this error occurs.

[Emmanuel]

This is the error i'm getting in line 27.

Warning: Size inputs must be scalar. This will error in a future release. > In New at 22 Warning: Size inputs must be scalar. This will error in a future release. > In New at 22 Error using * Inner matrix dimensions must agree.

Error in New (line 27) input = a*S;

[Stephen23]

An Aside: don't use i, j and input as variable names, as these are the names of inbuilt functions in MATLAB. You can use which to identify any existing functions, or help for more information on these specific functions.

Answer 1

[Ganesh P. Prajapat]

in line 27.. it should be >>input = a.*S as it requires term by term multiplication

Answer 2

[Image Analyst]

Paste in ALL the red error text, don't snip out small chunk of it like you did. Most likely something is a vector or array that you thought was a single scalar number. Or you're using * to do a matrix multiply instead of .* to do an element-by-element multiply.

[Image Analyst]

And what is the size of a and of S? Do this:

whos a
whos S

if a is m by n, then S must be n by p - the n's must be the same, that's just basic matrix math.

You might also look at this: http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/ so you can solve these things yourself LOTS faster. Debugging by Answers forum always takes longer.

Answer 3

[Stephen23]

Maybe this will help:

http://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html