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[SOLVED] define array to be 0 for all other values in Matlab

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frznchckn

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I've just started learning dsp and am going through a book and doing some FIR filter problems.

I have a sequence x = [1 3 7 8 10]

>> x = [1 3 7 8 10]
x =
1 3 7 8 10
>> x(1)
ans =
1
>> x(5)
ans =
10
>> x(-1)
??? Index exceeds matrix dimensions.
>> x(6)
??? Index exceeds matrix dimensions.

Is there an easy way to have all invalid matrix dimensions to just return 0? I can obviously write a function to check if the value is within the valid matrix dimensions, but I'm looking for a built-in Matlab function.

Thanks.
 

Matlab does not use negative indexing. If you want to have some kind of safeguard, you need an index check every time you address your vector, such as:
Code: 
if((n<1)||(n>5))
xn=0;
else
xn=x(n);
end
On the other hand, my preferred method, you can avoid all this complexity by calculating the index appropriately (just a little more work but worth the effort!).
 
So the answer is "no", I can't have Matlab assume 0 for all other index values.
 

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