error message when using dwt3

Hi there I get the following error message when trying to use dwt3. I have used dwt2 successfully but I get the following with this function

Undefined function or method 'dwt3' for input arguments of type 'double'.

Error in ==> part1reconstruct at 38 wt=dwt3(Adash,'bior2.4');

What do I need to change the data type to as I have looked at the documents and it does not say!

Thanks again guys :)

[Walter Roberson]

Is it possible you are using a version of MATLAB from before dwt3 was introduced? Which one are you using? What does

which -all dwt3
which -all dwt2

show ?

Answer 1

[Wayne King]

I think Walter's comment above is right on. dwt3.m should work if you have the Wavelet Toolbox and a version of MATLAB after dwt3.m was introduced (R2010a).

   X = randn(10,10,3);
   WT = dwt3(X,'bior2.4');

works.

Answer 2

[Bran]

Ahhh I think you're right guys! Thanks so much for the help! Yea when I put in which -all dwt3 it said dwt3 was not found but dwt2 was!

Was trying to use dwt3 because dwt2 keeps altering the dimensions of my matrix taking a 17x17x17 matrix to 17x17x3 :S

[Wayne King]

dwt2 is not appropriate for a 3-D matrix unless it's a true color image. That's why it is giving you x3 in the 3rd dimension, it's assuming that you are giving it a MxNx3 matrix.

[Bran]

Ah I see so I should always be using dwt3 right?

[Wayne King]

If you want to take the discrete wavelet transform of a 3-d dimensional dataset, then yes, you need to use 3-D transform. Are you sure you can use the 2-D wavelet transform on 2-D slices of your data?

[Bran]

No I think you are right I will need to use the 3-D transform.. many thanks for pointing this out to me :)