Msieve error when factoring long number

[donleon87]

I am trying to factor a large number however i get the following error when doing so. It is important to note that small numbers i have tried output correctly.


./msieve (some large number)

error -4 converting '(number)'


the number has a weird question mark as the last digit, and the number is over 900 characters.

[VBCurtis]

1. A question mark is not a digit- so get rid of that symbol if you want msieve to understand the number you're giving it. Or do you mean msieve adds that character? That may be because msieve shouldn't be asked to handle a number that size.
2. What kind of factoring are you hoping msieve does on a 900-digit number? I think you're using the wrong tool; ECM is what you want to be using, since NFS won't work.

[Happy5214]

Originally Posted by VBCurtis

2. What kind of factoring are you hoping msieve does on a 900-digit number? I think you're using the wrong tool; ECM is what you want to be using, since NFS won't work.

This. Download yafu or ecm.py, either of which would orchestrate the ECM stages. In yafu's case, if it finds enough factors in ECM to get it into NFS range (IIRC the record is around the 250-digit range, and for a solo effort it's realistically under 200 without a massive amount of hardware), it can run that too using GGNFS and msieve.