Limits of mpz_t size

[Gaj Satha]

Hi:

Are there any limits on the size of mpz_t in MPIR (Other than availble memory)?

I came to know that GNU GMP had limit of 41 billion on mpz_t sometime back (as per https://gmplib.org/list-archives/gmp-discuss/2016-July/006013.html), which they plan to remove but I don't know if it has been removed.

Please let me know. I need to calculate digits to 50 trillion.

Gaj

[Bill Hart]

The limits in MPIR are the same.

In order to get around the limit, you can use the mpn layer of functions.

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[Gaj Satha]

Is it correct in saying that these limits (41 billion) is related to sizeof(int) = 4?

My machine has sizeof(int) = 8, so I can allocate much more than 4GB using malloc. Will I still suffer from this limit of I can go much beyond it?

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[Bill Hart]

No it's 2^37 on a 64 bit machine. This is due to the 32 bit type used
for the limb count in the mpz_t struct.

If you want to use larger integers, use the mpn functions as I explained.

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