Int overflow in integer mod ring

[Martin Albrecht]

> ring r = (integer,2,32),(x,y,z),dp;
// ** You are using coefficients rings which are not fields.
// ** Please note that only limited functionality is available
// ** for these coefficients.
// **
// ** The following commands are meant to work:
// ** - basic polynomial arithmetic
// ** - std
// ** - reduce
// ** redefining r **
> 2*(2*x^30);
4x30
> 2*(2*x)^30;
-2147483648x30
> 2*(2^30);
// ** int overflow(*), result may be wrong
-2147483648

So it seems 2³² should not be allowed as base ring (since it is too big). This is on sage.math btw. which is a 64-bit Linux.

[hannes]

Has nothing to do with the ring: this is an overflow for the type int. For number (which depends on the ring and is here Z/2^{32 it works as expecteted: ....}

2*(2^{30); this is of type int}

int overflow(*), result may be wrong -2147483648

2*number(2^{30); this is of type number}

2147483648

_*2; also number

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