CoCoA » CoCoALib

23 Nov 2015

22:18 Bug #818: F5 with 3 args?

Arri's life is getting shorter by the minute -- grrr!
There is a 3 arg definition in @TmpF5Mat.C:867@, but the 3rd a... John Abbott

21:57 Bug #818: F5 with 3 args?

With 3rd formal arg commented out, it compiles and runs fine, but produces a different answer from before... :-/ At ... John Abbott

21:34 Bug #818 (In Progress): F5 with 3 args?

So why did this problem not appear earlier? And why did it appear now?
John Abbott

21:31 Bug #818: F5 with 3 args?

An easy workaround is just to comment out the 3rd arg in the declaration.
Since no one ever calls it with a 3rd arg ... John Abbott

21:28 Bug #818: F5 with 3 args?

If Arri comes my way I'll shorten his life by at least 2 hours -- the time I've wasted tracking this bug down. Grrr!... John Abbott

21:26 Bug #818 (In Progress): F5 with 3 args?

In @TmpF5.H@ two fns called @F5@ are declared: one (inline) with 2 args, and one with 3 args (3rd arg has a default v... John Abbott

19:25 Support #810 (Resolved): ILogBase: change name?

Checked in the renaming @ILogBase@ to @FloorLogBase@.
Currently the C5 manual page is single; it's what I'd done, an... John Abbott

15:03 Support #810: ILogBase: change name?

Same should be for @isqrt@! @FloorSqRt@? @FloorSqrt@?
Anna Maria Bigatti

14:56 Support #810: ILogBase: change name?

John Abbott wrote:
> Should the CoCoA-5 manual pages for @FloorLog2@ and @FloorLog10@ be separate from that for @Flo... Anna Maria Bigatti

14:37 Support #810 (In Progress): ILogBase: change name?

I've almost finished making the changes. I think @FloorLog2@ and @FloorLog10@ do improve readability of the code whe... John Abbott

11:19 Support #810: ILogBase: change name?

John Abbott wrote:
> Personally I think that *@FloorLogBase@* is too long. Anyway, the fn should expect two args (o... Anna Maria Bigatti

19:05 Feature #817 (New): GenRepr in CoCoALib?

At the Dagstuhl meeting last week some people were interested in having @GenRepr@ available in CoCoALib. I said it w... John Abbott

15:09 Design #816 (Closed): Rename isqrt to FloorSqrt (following ilog renaming to FloorLog)

Rename isqrt to FloorSqrt (following ilog renaming to FloorLog) John Abbott

14:48 Feature #812: PPMonoid pseudo-ctor without explicit ordering

John Abbott wrote:
> What about @NewPPMonoid("x", 10)@ as a shorthand for @NewPPMonoid(SymbolRange("x",0,10-1), StdD... Anna Maria Bigatti

13:19 Feature #812: PPMonoid pseudo-ctor without explicit ordering

What about @NewPPMonoid("x", 10)@ as a shorthand for @NewPPMonoid(SymbolRange("x",0,10-1), StdDegRevLex)@?
Or should... John Abbott

10:50 Feature #812: PPMonoid pseudo-ctor without explicit ordering

John Abbott wrote:
> We could slightly modify Mario's request:
> have new pseudo-ctors which do not need the orderi... Anna Maria Bigatti

10:35 Feature #812: PPMonoid pseudo-ctor without explicit ordering

I note that in issue #320 the main reason for rejection is that J and A disagreed about what symbol names should be u... John Abbott

10:29 Feature #812 (New): PPMonoid pseudo-ctor without explicit ordering

Mario asked about having an easy way to create a @PPMonoid@ without specifying explicitly the ordering (or even the n... John Abbott

14:40 Design #815: GlobalManager: Imminent disaster should be a proper error

I have put the lines into a separate (static member) function. What should it be called?
Currently I have called ... John Abbott

14:04 Design #815 (In Progress): GlobalManager: Imminent disaster should be a proper error

The real problem with @terminate@ is that it gives the program no chance to handle the situation; in fact the only "b... John Abbott

13:57 Design #815: GlobalManager: Imminent disaster should be a proper error

The real problem is that the check for still-existing @RingElem@ values occurs inside the dtor for @GlobalManager@, a... John Abbott

13:25 Design #815: GlobalManager: Imminent disaster should be a proper error

I've just made some big changes to matrices for orderings: everything compiles, but @test-F5@ produces "imminent disa... John Abbott

13:23 Design #815 (Closed): GlobalManager: Imminent disaster should be a proper error

During destruction @GlobalManager@ checks the ref counts of @RingQQ@ and @RingZZ@; if they are too large then "Immine... John Abbott

13:08 Design #311: XelMat, StdDegRevLexMat, ... should be MatrixView

I notice only now that these pseudo-ctors take only the dimension as arg; *what should the ring of the matrix be?*
... John Abbott

11:49 Bug #814 (Closed): PPOrdering: matrix ordering, what rings are allowed.

I think that @NewMatrixOrdering@ does not check the ring of the matrix handed to it.
Check if I am right; anyway, ... John Abbott

11:39 Feature #813 (Feedback): Implement "elim" in CoCoALib

In CoCoALib we have member function @myElim@.
Choose and implement the "proper" function.
Anna Maria Bigatti

11:13 Feature #811: Add new fn SimplestBinaryRatBetween

John Abbott wrote:
> Checked in. Should be OK, but I do have some other files "pending", so it is possible I missed... Anna Maria Bigatti

10:41 Design #786: MemPool: review min and max loaf sizes

John Abbott wrote:
> Did you also try tests which create lots of ring elements? Maybe a non-trivial GBasis?
I tr... Anna Maria Bigatti

10:23 Support #774: Rename file PPMonoidEvZZ

We could simply merge the code in @PPMonoidEvZZ@ into @PPMonoidEv@.
What do you think?
Are they similar enough th... John Abbott

21 Nov 2015

20:19 Feature #811: Add new fn SimplestBinaryRatBetween

Checked in. Should be OK, but I do have some other files "pending", so it is possible I missed something -- can you ... John Abbott

14:49 Feature #811 (Feedback): Add new fn SimplestBinaryRatBetween

Implemented; documented (also C5); added test (NumTheory3)
John Abbott

14:48 Feature #811 (Closed): Add new fn SimplestBinaryRatBetween

In some applications it is helpful to use "binary rationals" (denom is a power of 2).
Add a new fn *@SimplestBinaryR... John Abbott

15:09 Feature #440: Port RealRoots to C++

After the SC^2 meeting it is clear that several people would like @RealRoots@ to be ported into C++. If the project ... John Abbott

11:27 Design #786 (In Progress): MemPool: review min and max loaf sizes

Did you also try tests which create lots of ring elements? Maybe a non-trivial GBasis? John Abbott

20 Nov 2015

17:26 Design #786: MemPool: review min and max loaf sizes

John Abbott wrote:
> Change @MinLoafBytes@ to 4*1024. Maybe you could also try 1024.
> Change @MaxLoafBytes@ to 64... Anna Maria Bigatti

15:01 Design #786: MemPool: review min and max loaf sizes

John Abbott wrote:
> Are the problems my fault? Or some problem with the interface of @MemPool@? :-(
no, my pro... Anna Maria Bigatti

14:38 Design #786: MemPool: review min and max loaf sizes

Are the problems my fault? Or some problem with the interface of @MemPool@? :-(
John Abbott

14:36 Support #810: ILogBase: change name?

Personally I think that *@FloorLogBase@* is too long. Anyway, the fn should expect two args (of which the second is ... John Abbott

14:34 Support #810 (Closed): ILogBase: change name?

I was wondering about using a better name for @ILogbase@.
I used it recently in a new function, and couldn't remembe... John Abbott

19 Nov 2015

15:06 Design #786: MemPool: review min and max loaf sizes

about to try..
(some compilation problems...) Anna Maria Bigatti

06:50 Design #809 (New): FastCmp for degree -- useful?

Is the function @FastCmp@ for @degree@ actually useful?
Check whether it is perceptibly faster than @cmp@; if so, ... John Abbott

18 Nov 2015

23:29 Bug #808: Alg Extn by non-zero dim ideal

The following variant works OK:... John Abbott

23:28 Bug #808 (New): Alg Extn by non-zero dim ideal

The following produces an NYI error for the reciprocal:... John Abbott

14 Nov 2015

22:14 Design #592: Review design of ConstMatrixView

I've still got problems with the new (internal) design for @BlockMat2x2@. While investigating I was quite surprised ... John Abbott

20:34 Bug #807: DiagMat: mySetEntry checks the entry is writable only if debugging active

As a general rule we say that mem fns do not perform arg sanity checks because such checks are the responsibility of ... John Abbott

20:28 Bug #807 (Rejected): DiagMat: mySetEntry checks the entry is writable only if debugging active

The mem fn @mySetEntry@ for @DiagMat@ checks that the indices indicate a diagonal element only if @CoCoA_DEBUG@ has b... John Abbott

20:24 Design #806: AssignZero for matrix

In some ways it would be nice to have a default impl of @AssignZero@; presumably as the mem fn @MatrixView::myAssignZ... John Abbott

20:16 Design #806 (In Progress): AssignZero for matrix

Before spending too much time deciding the exact semantics, we should also decide if the procedure is even useful -- ... John Abbott

20:08 Design #806 (Closed): AssignZero for matrix

There is a procedure @AssignZero@ for a matrix; it calls the mem fn @myAssignZero@.
What should these fns do? John Abbott

14:50 Design #311: XelMat, StdDegRevLexMat, ... should be MatrixView

I've implemented the other defn of @StdDegRevLexMat@; we can decide later which impl will remain "active".
John Abbott

13 Nov 2015

14:51 Design #805: New type for "constant" matrices?

As predicted in comment 1, there is a problem with @BlockMat2x2@. Not yet sure how to deal with it :-/
John Abbott

13:45 Design #805: New type for "constant" matrices?

In principle the concrete classes for @IdentityMat@ and so on could derive from @matrix@ but then they have to impl l... John Abbott

11:19 Design #805 (In Progress): New type for "constant" matrices?

I believe that @ConstMatrixView@ is not the right type, because a matrix "view" is a way of looking at another object... John Abbott

10:49 Design #805 (Closed): New type for "constant" matrices?

I believe that implementing @IdentityMat@, @StdDegRevLexMat@ and so on as objects of type @ConstMatrixView@ is not co... John Abbott

13:01 Design #311: XelMat, StdDegRevLexMat, ... should be MatrixView

What do we want the @StdDegRevLexMat@ to be?
There are two obvious candidiates: here are 3x3 instances... John Abbott

12 Nov 2015

14:51 Bug #804 (In Progress): ZeroMat and IdentityMat should produce a matrix not a ConstMatrixView

Rather to my surprise I have failed to create an example where @ZeroMat@ (or @IdentityMat@) misbehaves -- no idea why... John Abbott

14:22 Bug #804 (Closed): ZeroMat and IdentityMat should produce a matrix not a ConstMatrixView

I think that @ZeroMat@ and @IdentityMat@ should produce a result of type @matrix@ and not one of type @ConstMatrixVie... John Abbott

11 Nov 2015

18:19 Design #311: XelMat, StdDegRevLexMat, ... should be MatrixView

After some hasty cut-and-paste work I have some code which compiles :-)
I'm not so foolish as to try running it... t... John Abbott

17:30 Design #311: XelMat, StdDegRevLexMat, ... should be MatrixView

JAA is convinced that this is a good idea.
To get it finished quickly I shall ignore issue #592; it probably shoul... John Abbott

16:35 Design #602: OrdMat: should it be a reference to a MatrixView in all PPOrderings?

JAA now thinks that there is an example (see issue #803) where it could be useful to have the order matrix(view) quic... John Abbott

13:35 Design #602: OrdMat: should it be a reference to a MatrixView in all PPOrderings?

How important is it that @OrdMat@ is fast? Is there a good example where we would want to compute repeatedly the @Or... John Abbott

14:19 Feature #803 (In Progress): PPOrdering: use it to compute WDeg?

The main task I want to simplify is that of implementing @myWDeg@, @myCmpWDeg@ and @myCmpWDegPartial@ for @PPMonoidSp... John Abbott

13:43 Feature #803 (In Progress): PPOrdering: use it to compute WDeg?

Should objects of type @PPOrdering@ be able to compute WDeg vectors and/or individual components of WDeg vectors?
... John Abbott

13:47 Slug #799: vector of "indets" in each PPMonoid?

I have lowered the priority of this issue because it will take some time to complete, and the resulting improvement w... John Abbott

10:01 Slug #799 (In Progress): vector of "indets" in each PPMonoid?

As far as I can tell @PPMonoidBase::myIndets@ is used only once, in the (inefficient) fn @PPMonoidBase::mySymbolValue... John Abbott

12:15 Feature #802: DivMask: extend interface?

John Abbott wrote:
> I think updating would mean replacing the div-mask with that for the LCM of the old value and t... Anna Maria Bigatti

10 Nov 2015

18:39 Feature #800: PPMonoidSparse: impl of sparse PPs

John Abbott wrote:
> Might it be important to store the @StdDeg@ along with the list of (index, exp) pairs? If it i... Anna Maria Bigatti

16:45 Feature #800: PPMonoidSparse: impl of sparse PPs

For @Wdeg@ I am inclined to compute it "on the fly" every time it is needed. If someone reports poor execution speed... John Abbott

15:16 Feature #800: PPMonoidSparse: impl of sparse PPs

The currently missing functions are: @myCmp@, @myWDeg@ and @myCmpWDeg@ (& a partial version). Also @myComputeDivMask... John Abbott

14:49 Feature #800 (In Progress): PPMonoidSparse: impl of sparse PPs

There was a very incomplete impl in @PPMonoidSparse.C@, which was already recognized by @Makefile@.
Apparently the... John Abbott

18:38 Feature #802: DivMask: extend interface?

I think updating would mean replacing the div-mask with that for the LCM of the old value and the new indet-power. T... John Abbott

18:33 Feature #802: DivMask: extend interface?

John Abbott wrote:
> If we do extend the interface of @DivMask@ to accommodate the sparse repr, what should the exte... Anna Maria Bigatti

16:15 Feature #802: DivMask: extend interface?

If we do extend the interface of @DivMask@ to accommodate the sparse repr, what should the extended interface expect:... John Abbott

16:09 Feature #802 (In Progress): DivMask: extend interface?

Currently the only way to make a (non-trivial) @DivMask@ is to use the function @myAssignFromExpv@ which clearly suit... John Abbott

15:57 Feature #802 (In Progress): DivMask: extend interface?

The new @PPMonoidSparse@ impl needs to supply a @myComputeDivMask@ mem fn.
The current interface is well suited to... John Abbott

10:17 Feature #747: New function for making list of symbols (indeterminate names)

That's fine by me -- less work for me :-)
Indeed @symbols("x[1..3,2..5]")@ is not really that much more readable tha... John Abbott

09 Nov 2015

23:22 Feature #747: New function for making list of symbols (indeterminate names)

John Abbott wrote:
> Do we want this function to handle symbol ranges?
>
> It probably makes sense for @symbols... Anna Maria Bigatti

15:21 Feature #747: New function for making list of symbols (indeterminate names)

Do we want this function to handle symbol ranges?
_e.g._ @symbols("x[1..3,2..5]")@ would produce the same result as ... John Abbott

15:46 Feature #801: Test whether a symbol is in a ring

Currently this operation is implemented in a hidden way inside @RingBase::myNew(symbol)@.
The implementation there... John Abbott

15:39 Feature #801 (New): Test whether a symbol is in a ring

Should there be a function which tests whether a given @symbol@ is in given @ring@?
I am thinking of "recursive" s... John Abbott

13:35 Feature #800: PPMonoidSparse: impl of sparse PPs

I had assumed that this issue already existed, but a quick search did not find it.
There is already a partial impl... John Abbott

13:33 Feature #800 (Closed): PPMonoidSparse: impl of sparse PPs

Implement a PPMonoid which uses a sparse repr for the PPs.
This is useful when there are many indets.
John Abbott

13:30 Slug #799: vector of "indets" in each PPMonoid?

The vector of indets is used in the (mem) function @mySymbolValue@, which currently returns a reference to the image ... John Abbott

13:26 Slug #799 (In Progress): vector of "indets" in each PPMonoid?

Is it truly useful to have each PPMonoid keep a vector of its own indets?
This is not a problem if the indets are ... John Abbott

07 Nov 2015

22:35 Feature #797 (In Progress): SmallFpImpl: make it faster

The speed gains varies form platform to platform -- surprise, surprise!
The old @DUPFF@ code was (significantly) f... John Abbott

21:57 Feature #797 (In Progress): SmallFpImpl: make it faster

After comparing @gcd@ for @DUPFp@ and @DUPFF@, I saw that the latter was significantly faster (_e.g._ factor 2 or mor... John Abbott

05 Nov 2015

16:45 Feature #796 (Closed): CoCoALib function for radical (or SqFree) of a polynomial

This problem is generally easier than @SqFreeFactor@, indeed in @SqFreeFactorPosDerChar0@ it is just computed by the ... Anna Maria Bigatti

16:16 Feature #48: Squarefree factorization - multivariate polynomials, char 0

Anna Maria Bigatti wrote:
> John Abbott wrote:
> > I'm not sure; I suspect it will not work in every case.
>
> I... Anna Maria Bigatti

16:14 Feature #48: Squarefree factorization - multivariate polynomials, char 0

Good point! So if @gcd@ works then we can expect that squarefree decomposition works. John Abbott

15:06 Feature #48: Squarefree factorization - multivariate polynomials, char 0

John Abbott wrote:
> I'm not sure; I suspect it will not work in every case.
I thought it would: in char 0 the squar... Anna Maria Bigatti

16:01 Bug #793: compilation on fedora 23: some worrying "error messages"

The *@Fatal error@* messages appeared once again when I tried building CoCoALib from a new unpackaged tar file. The ... John Abbott

15:41 Feature #795 (Feedback): Add new fn InvModNoCheck

Implemented, documented. No separate test; it is effectively tested inside @test-NumTheory1@
John Abbott

15:39 Feature #795 (Closed): Add new fn InvModNoCheck

For efficiency it would be nice to have public access to the "fast" function for computing inverses modulo an integer.
John Abbott

15:37 Design #649 (Feedback): Make SmallFpImpl safer to use

[oops cut-and-paste did the wrong thing]
Changing to feedback; implemented the fn mentioned in comments 18-20. See #795 John Abbott

13:47 Design #649: Make SmallFpImpl safer to use

John Abbott wrote:
> I am thinking of the name @InvModNoCheck@; it is pretty clear; it is a bit long, so that ought ... Anna Maria Bigatti

13:17 Design #649: Make SmallFpImpl safer to use

I am thinking of the name @InvModNoCheck@; it is pretty clear; it is a bit long, so that ought to discourage "casual ... John Abbott

11:49 Design #649: Make SmallFpImpl safer to use

In @NumTheory.H@ there is a fn called @InvMod@ which expects two @MachineInt@; internally it calls the fn @InvMod_pri... John Abbott

11:15 Design #649: Make SmallFpImpl safer to use

I have resolved the mystery of the two identical functions running at different speeds: my test program was giving (v... John Abbott

04 Nov 2015

19:41 Design #649 (Resolved): Make SmallFpImpl safer to use

I have implemented @NonRedValue@.
Checked everything last night; revised examples, doc, etc.
Checked in today.
T... John Abbott

03 Nov 2015

22:59 Feature #48: Squarefree factorization - multivariate polynomials, char 0

I'm not sure; I suspect it will not work in every case.
What coeff ring did you have in mind? Were you thinking o... John Abbott

17:26 Feature #48: Squarefree factorization - multivariate polynomials, char 0

In @factor.C@ there is the line:... Anna Maria Bigatti

16:15 Bug #793: compilation on fedora 23: some worrying "error messages"

I'm compiling some other programs; compilation time varies from 2mins to almost 5mins. I'll ask the technical guy if... John Abbott

15:00 Bug #793: compilation on fedora 23: some worrying "error messages"

I'm recompiling (with full debugging), and the mysterious @Fatal error@ messages have not reappeared; and anyway desp... John Abbott

14:45 Bug #793: compilation on fedora 23: some worrying "error messages"

John Abbott wrote:
> The new computer took *100mins* to compile and run the examples. Just running the examples take... Anna Maria Bigatti

12:56 Bug #793 (In Progress): compilation on fedora 23: some worrying "error messages"

The new computer took *100mins* to compile and run the examples. Just running the examples takes only 30secs.
John Abbott

11:34 Bug #793: compilation on fedora 23: some worrying "error messages"

I shall try to investigate this, but it may take a long time. The new computer seems to be quite fast (_e.g._ more t... John Abbott

14:15 Design #794 (Rejected): ar gives warnings on fedora 23

The archive creator @ar@ gives warnings about the use of @u@ flag with the @r@ flag (because the default is @D@).
... John Abbott

11:31 Design #649: Make SmallFpImpl safer to use

I quite like @NonRedValue@; it is quite clear, and a bit long (to discourage "casual use"). I'll try changing the co... John Abbott

02 Nov 2015

15:53 Design #649: Make SmallFpImpl safer to use

John Abbott wrote:
> There is a question about names:
> * *@SmallFpImpl::value@* is the class for reduced values
>... Anna Maria Bigatti

15:01 Bug #793 (Closed): compilation on fedora 23: some worrying "error messages"

Compilation on the new computer (with fedora 23, due for release tomorrow ?!!? according to Wikipedia) produced sever... John Abbott

14:41 Slug #792: configure: search for libgmp too slow

Since I believe that the @find@ command is the culprit, the solution would be to eliminate it. This could be done by... John Abbott

14:39 Slug #792: configure: search for libgmp too slow

The situation was the following. The new computer did not have GMP installed, so the attempt to use @-lgmp@ failed, ... John Abbott

14:16 Slug #792 (Closed): configure: search for libgmp too slow

I have new computer (here in Kassel). I am trying to build CoCoALib/CoCoA-5. The @configure@ script took *ages* to ... John Abbott

30 Oct 2015

18:49 Design #649: Make SmallFpImpl safer to use

When a @SmallFpImpl@ is printed currently it appears as @SmallFpImpl(p)@ where @p@ is the prime. Should the export c... John Abbott

18:45 Design #649: Make SmallFpImpl safer to use

I am not entirely happy with the length of the names for the export conventions:
* *@GlobalSettings::SymmResidues@*
... John Abbott

16:06 Design #649: Make SmallFpImpl safer to use

I like all types in CoCoALib to be printable; naturally this includes *@value@* and *@uvalue@*.
@SmallFpImpl@ offers... John Abbott

10:56 Design #649: Make SmallFpImpl safer to use

I now disagree with my comment number 3. I think that the impl using new types (classes) to represent the values is ... John Abbott

10:47 Support #791: Clean code for DistrMPolyClean

I'm hoping Anna will "volunteer" to do this ;-)
John Abbott

29 Oct 2015

21:55 Bug #784: threadsafety: Scott Meyers's advice about cached values

Victor Shoup said he made NTL threadsafe (using C++11) Anna Maria Bigatti

14:52 Bug #790: RingDistrMPolyInlFpPPImpl::mySummandPool frees ZERO PTR many times

John Abbott wrote:
> Now I am slightly undecided which implementation I prefer:
> Impl *(A)*:
> [...]
> Impl *(B)... Anna Maria Bigatti

11:56 Bug #790: RingDistrMPolyInlFpPPImpl::mySummandPool frees ZERO PTR many times

Now I am slightly undecided which implementation I prefer:
Impl *(A)*:... John Abbott

14:04 Support #791 (New): Clean code for DistrMPolyClean

There is quite a lot of cruft in @DistrMPolyClean.C@.
Remove everything that is no longer needed.
Perhaps also chec... John Abbott

14:02 Bug #680 (Resolved): DistrMPolyClean does not use MemPool for summands?

I have now revised the code so that it uses its @MemPool@ for summands; essentially I had to "steal" the idea of @New... John Abbott

28 Oct 2015

18:29 Design #789: NumTheory: behaviour of InvMod when inverse does not exist

John Abbott wrote:
>
> Making @InvMod@ throw an exception is an interface change, so it could in principle break... Anna Maria Bigatti

15:25 Bug #790 (Resolved): RingDistrMPolyInlFpPPImpl::mySummandPool frees ZERO PTR many times

The problem was a missing pair of curly brackets around a "then" clause comprising two commands (location @DistrMPoly... John Abbott

11:15 Bug #790: RingDistrMPolyInlFpPPImpl::mySummandPool frees ZERO PTR many times

I compiled CoCoALib with the @MemPool@ debugging options active.
In @test-SparsePolyRing1.C@ I inserted the followin... John Abbott

11:12 Bug #790 (Closed): RingDistrMPolyInlFpPPImpl::mySummandPool frees ZERO PTR many times

I have run @test-SparsePolyRing1@ with @MemPool@ verbose active, and there were lots of warnings about freeing @ZERO ... John Abbott

26 Oct 2015

11:54 Design #789 (In Progress): NumTheory: behaviour of InvMod when inverse does not exist

Currently @InvMod(r,m)@ returns 0 if no inverse exists. This is simple to implement, and can easily be used by the c... John Abbott

11:43 Design #789 (Closed): NumTheory: behaviour of InvMod when inverse does not exist

Currently @InvMod(r,m)@ returns 0 if there is no inverse of @r@ modulo @m@.
Should it throw an exception (presumab... John Abbott