Matrix Dimension must agree - Vectorization

Hi there,

I created a function called Fx which takes an single number as input and produce a 1 single number as output.

I tried to run:

n = 1:10;
r = Fx(n);

What I expected is an array of r 1x10, each contains the result of Fx of n from 1 to 10.

However, I got "Matrix dimensions must agree" instead. This does not make sense to me. I tried to run it with for loop and it worked just fine.

for n = 1:10
r(n) = Fxl(n);
end

The array involved in the calculation of Fx is 115824. So I tried with array n of 1x115824 then the code only return the result of n(1,1) only.

Does anyone know what's going on here?

If so, please let me know.

Thank you

[KSSV]

What is ComplexIntegral?

[madhan ravi]

Without seeing the function , how can a solution be suggested?

[Toan Nguyen]

My bad. Here it is.

function [result] = Fx(w)
%UNTITLED Summary of this function goes here
%   Detailed explanation goes here

load hw11.mat
%load the audio file with  Fs = 44100 and the audio matrix "toan"

toan = reshape(toan,[1,115824]);
%reshape the 1115824x1 to 1x115824

n = 1:length(toan);

t = timearray(n);
%Create an array of t which is 1x115824

a = audio(n);
%Create an array of a which is 1x115824

sgma = zeros(1,length(n));
%Create sigma array 1x115824

e = exp(1)*ones(1,length(n));
%Create exponential array 1x115824

omega = -(sgma +j*w);
%Create omega array 1x115824

c = a.*e.^(omega.*t);
%Element wise calculation. The c matrix is 1x115824

result = sum(c);
%Sum of all element of c.

end

[madhan ravi]

Did you use w inside the function?

[Toan Nguyen]

Yes I did.

I create the omega array with w: omega = -(sgma + j*w);

sgma is the 1x115824 matrix.

[madhan ravi]

 r = cell(10, 1); % before loop
 r{n} = ... % inside loop the rest remains unchanged

[Toan Nguyen]

Thank you for your help.

Could you elaborate on what happened in your code so I can look into it.

Also, what do you mean by "before loop" and "inside loop"? I don't have "for loop" nor "while loop" in my code. Are you refering to the Function file?

Thank you

[madhan ravi]

“I tried to run it with for loop and it worked just fine.”

What is the problem then??

[Toan Nguyen]

I'm sorry that I did not clarify the objective.

For loop is slow with 100 runs already and my aim is around 100k.

From what I heard, vectorization is faster. Thus, that's what I'm trying to do

Answer 1

[Mahesh Taparia]

Hi

It seems you want to apply a function on each element of an array without applying for loop. In this case, create that function according to the input, i.e, give array as the function input and apply the whole computation on that array which finally returns a vector as functional output.