There is a mistake with such expressions as mod(23^12,24). MATLAB gives an answer of 0 which, given that 23 and 24 are relative primes,
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AdamE
am 12 Jun. 2019
Kommentiert: AdamE
am 12 Jun. 2019
Clearly, 23 = -1 mod 24. So, mod(23^12,24) should result in 1.
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Rik
am 12 Jun. 2019
The number you're trying to process is larger than flintmax(), so you can rely on single digit precision operations.
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AdamE
am 12 Jun. 2019
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Walter Roberson
am 12 Jun. 2019
No, it should not be. Doing that would require rewriting the entire way that MATLAB operates on parameters.
MATLAB currently always evaluates all parameters before the function is called, so when you call mod(23^12, 24) then 23^12 and 24 are evaluated and their full evaluated results are passed to mod() .
In order for MATLAB to do what you are suggesting automatically, it would have to somehow record the formula 23^12 and 24 and pass that into mod() and then mod would have to know how to decompose formulas in terms of modular arithmetic. It would have to be pretty deep, such as knowing that
mod( (23^12)^3 + 5*23^12 + 7, 24)
could be reduced in modular arithmetic.
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