I'm designing a Recurrent NN for English letter Prediction. Basically, input vectors is n-1, n-2, ..., 1, etc letter history. The output is predicted letter. I'd like to use decimal ASCII as the input and output values.

But the result does reflect my ideal. I suspect the 'decimal ASCII ' could be a problem. Any advice?

PS: It seems not too many matlab applications are related to "the letter input". why? If there are, could you please give recommendation