Opened 13 years ago

Closed 13 years ago

Last modified 13 years ago

#312 closed bug (invalid)

basefield real: subst for parameters does not work

Reported by: gorzel Owned by: hannes
Priority: minor Milestone: 3-1-3 and higher
Component: singular-kernel Version: 3-1-2
Keywords: Cc:

Description

Compare:

> ring r0 = (0,t),x,dp;
> poly f = tx+2;
> subst(f,x,1/2);
(1/2t+2)
> subst(f,t,1/2);   // OK in char 0 for parameters
1/2*x+2

> ring rr = (real,t),x,dp;
> poly f = tx+2;
> subst(f,x,1/2);
(2+t*0.5)
> subst(f,t,1/2);    // fails for parameters with real
   ? ringvar/par expected
   ? error occurred in or before STDIN line 10: `subst(f,t,1/2);`

Change History (2)

comment:1 Changed 13 years ago by hannes

Resolution: invalid
Status: newclosed

This is as it should be:

ring rr = (real,t),x,dp;
rr;
//   characteristic : 0 (complex:6 digits, additional 6 digits)
//   1 parameter    : t 
//   minpoly        : (t^2+1)
//   number of vars : 1
//        block   1 : ordering dp
//                  : names    d
//        block   2 : ordering C

and one should not be able to substitute sqrt(-1) by 1/2.

Last edited 13 years ago by hannes (previous) (diff)

comment:2 Changed 13 years ago by gorzel

War mir bisher nicht bekannt, dass real mit Parameter sich automatisch wie complex verhaelt.

> ring rr = (real,t),x,dp;
> rr;
//   characteristic : 0 (complex:6 digits, additional 6 digits)
//   1 parameter    : t 
//   minpoly        : (t^2+1)
//   number of vars : 1
//        block   1 : ordering dp
//                  : names    x
//        block   2 : ordering C
> ring rc = complex,x,dp;
> rc;
//   characteristic : 0 (complex:6 digits, additional 6 digits)
//   1 parameter    : i 
//   minpoly        : (i^2+1)
//   number of vars : 1
//        block   1 : ordering dp
//                  : names    x
//        block   2 : ordering C
> ring rct = (complex,t),x,dp;
> rct;
//   characteristic : 0 (complex:6 digits, additional 6 digits)
//   1 parameter    : t 
//   minpoly        : (t^2+1)
//   number of vars : 1
//        block   1 : ordering dp
//                  : names    x
//        block   2 : ordering C
}


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