Convolving in Matlab

This is the code.

clear all;
i = 0;
j = 0;
folder = uigetdir;
Loaddata(folder)

for i=1:4833
  %Reads in rows of numbers representing waveforms into a new vector
  A(i,:) = Acquisitions(i,:)-32000;

end

    t = -pi:0.01:pi;
    B = tripuls(t);
for j=1:4833

    W(j,:) = conv2(B,A(j,:));
end

And it keeps giving me this error: ??? Undefined function or method 'conv2' for input arguments of type 'int16'.

Error in ==> readinmaqscall at 18 W(j,:) = conv2(B,A(j,:));

So basically I am trying to convolve a triangular pulse with a bunch of different waveforms I have collected and this is the best way I know of going about it. It keeps giving me an error based on the type of data in the vectors. I am unsure what format it needs to be in for convolving.

Answer 1

[Andrew Newell]

You should convert to double:

W(j,:) = conv(double(B),double(A(j,:)));

You can use conv2. As for the type, if I enter something like

conv(unit8(u),v)

for some vectors u and v, I get the message:

Warning: CONV2 on values of class UINT8 is obsolete.
       Use CONV2(DOUBLE(A),DOUBLE(B)) or CONV2(SINGLE(A),SINGLE(B)) instead.

So that gives you some idea of the options.

EDIT: I don't know why conv2 doesn't accept integer types because it is a built-in function. However, if you input a double array with integer values, it will return a double array with integer values (see the article in Steve on Image Processing for an example).

[Cole]

Thanks, I just realized that it worked with doubles, is there a reason for this? is a double all you can use with conv?

Answer 2

[Qiu]

I meet the same problem.

MATLAB keeps showing:

Undefined function or method 'conv2' for input arguments of type 'double' and attributes 'full 3d real'

[Image Analyst]

You need to pass it a grayscale image, not a color (3D) image.

Answer 3

[bym]

I think you want

conv()

instead of

conv2

[Cole]

I am sorry I forgot to mention it but I have tried conv() as well and it gives me the same error.