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Feature #484

Evaluate in other ring (was called :: in CoCoA-4)

Added by John Abbott about 10 years ago. Updated over 9 years ago.

Status:
Closed
Priority:
Normal
Assignee:
Anna Maria Bigatti
Category:
CoCoA-4 function to be added
Target version:
CoCoA-5.1.1 Seoul14
Start date:
19 Mar 2014
Due date:
% Done:

100%

Estimated time:
1.51 h
Spent time:
1.50 h

Description

CoCoA-4 has the :: operator which evaluated expressions in a given ring:

R::x+y

2014-07: added ReadExpr
PolyAlgHom(P1, P2, [ReadExpr(P2,"a^2"), ReadExpr(P2,"b^3")])

Related issues

Related to CoCoA-5 - Feature #606: Evaluate in ring operator (was called :: in CoCoA-4)Closed2014-03-19

History

#1 Updated by John Abbott about 10 years ago

  • Project changed from CoCoA to CoCoA-5

Sorry, I thought I was already in CoCoA-5

#2 Updated by John Abbott about 10 years ago

  • Subject changed from Evaluate in ring operator (:: in CoCoA-4) to Evaluate in ring operator (was called :: in CoCoA-4)

We must determine the exact semantics (C4 was pretty vague, I believe).
We should decide what syntax to use.

It might help solve the problem about printing matrices (#18 post 3).

#3 Updated by Anna Maria Bigatti about 10 years ago

  • Category set to CoCoA-4 function to be added
  • Target version set to CoCoA-5.1.0 Easter14

That would be handy! But I expect it to be hard to implement.

Right now the closer you can get to it is 

PolyAlgHom(P1, P2, [RingElem(P2,"a")^2, RingElem(P2,"b")^3]);

I would suggest forcing parentheses

PolyAlgHom(P1, P2, P2::([a^2,b^3]) );

#4 Updated by John Abbott about 10 years ago

  • Target version changed from CoCoA-5.1.0 Easter14 to CoCoA-5.?.?

#5 Updated by Anna Maria Bigatti almost 10 years ago

  • Assignee set to Anna Maria Bigatti
  • Target version changed from CoCoA-5.?.? to CoCoA-5.1.1 Seoul14
  • % Done changed from 0 to 10
  • Estimated time set to 1.00 h

In CoCoALib we can read expressions from strings with ReadExpr(RING, STRING).
I'm going to add it to cocoa-5 so you can write:

PolyAlgHom(P1, P2, [ReadExpr(P2,"a^2"), ReadExpr(P2,"b^3")]);

and more complicated expressions like
ReadExpr(R,"(x+y)*(x^3-2*y-1)");

#6 Updated by Anna Maria Bigatti almost 10 years ago

ReadExpr documented, cvs-ed
(updated entry for RingElem)

#7 Updated by Anna Maria Bigatti almost 10 years ago

  • % Done changed from 10 to 50

#8 Updated by Anna Maria Bigatti over 9 years ago

  • Status changed from New to In Progress

#9 Updated by Anna Maria Bigatti over 9 years ago

  • Subject changed from Evaluate in ring operator (was called :: in CoCoA-4) to Evaluate in other ring (was called :: in CoCoA-4)
  • Status changed from In Progress to Feedback
  • % Done changed from 50 to 90

#10 Updated by Anna Maria Bigatti over 9 years ago

  • Estimated time changed from 1.00 h to 1.51 h

#11 Updated by Anna Maria Bigatti over 9 years ago

the CoCoA-4 operator "::" is now in another specific issue.
For the time being I think that ReadExpr may be good enough.

#12 Updated by John Abbott over 9 years ago

  • Status changed from Feedback to Closed
  • % Done changed from 90 to 100

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