On 6/19/24 01:07, Murilo wrote:
I've created a software which performs the Fermat's Primality Test,
however if I input a very big number it causes an error saying "Illegal
instruction (core dumped)". Does anyone know why?
I've used GDB and here is the message:
Program received signal SIGILL, Illegal instruction.
0x00005555555e40b0 in
_D3std8internal4math11biguintcore7BigUint3powFNaNbNfNkMSQCcQCbQBvQBtQBjmZQs ()
Here is the link to the source code:
https://github.com/MuriloMir/Fermat-primality-test
Looking at the code, this is probably the cause:
```
if (BigInt(tester) ^^ number % number != tester)
```
This uses roughly as much memory as `number` is big, times the `log` of
`tester`. You'd have to implement your own modular exponentiation that
does not compute the full intermediate result, the you use only roughly
`log` of `number` memory.
