the question seems simple as using mod works for small numbers not for large numbers.
i want to calculate mod( (4^15)*(21^13),47) the matlab ans= 21 but the correct ans = 3 using the windows calculator. is there any way in matlab to calculate such modulus ?
Thanks in advance.
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See this newsgroup thread where Bruno Luong gives advice on how to do this calculation without using the symbolic toolbox:
The number you describe is far too large for accurate numerical computation using only 'double' floating points numbers. However, the 'mod' function also works with symbolic numbers using the symbolic toolbox. You can compute with these to any accuracy you wish.
mod(mod( (4^15), 47) * mod((21^13),47), 47)
Thanks for your help any way , but even the powermod function or any of the above functions in url links can calculate the correct answer which is 3 .
powermod( (4^15) * (21^13) , 1 , 47 ) gives 21 but the correct ans using windows calculator is 3 and it is equivelant to the answer in my cryptography study book .
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