>Is a 4x2000 matrix (4 is no of features & 2000 is total no of samples collected), a correct way of preparing input matrix?
Yes
>Should the samples in input matrix be sequential or random?
With default batch training (e.g.,trainlm or trainscg) it doesn't make any difference.
However, with sequential training (e.g., adapt) randomize.
>Also, considering 20 alphabets, should there be 20 classes?
Yes
> How should my target matrix look like? Should it be 20x2000?
Yes. Each column should be a column from the 20-dimensional unit matrix eye(20).
Use ind2vec to create the target matrix t from the true integer class indices.
Use vec2ind to obtain predicted class indices from the output y.
Nerr = sum(predclassind ~ trueclassind)
Hope this helps.
Thank you for formally accepting m answer!
Greg
