> > BTW2: The 'Pfaffian' function starts with an
> > upper case letter. I think the convention for
> > functions is lower case, isn't it?
>
> > A similar issue is 'mrv_limit' which is not
> > camel case.
>
> > It's besselJ, besselY, ...
>
> I think FriCAS should stick to the convention that types (domains,
> categories, and packages) start with an uppercase letter and functions
> with a lowercase letter and all names use camelcase.
So this convention is still up and supported. That's good, I
think is very useful. It makes it easier for beginners to
learn using the Axiom System. (It really helped me a lot.)
> So yes, I would be in favour of renaming Pfaffian to pfaffian and
> remove the "mrv_" in front of all exports from the MrvLimitPackage.
Ok, I prepared a patch.
If we all agree on this change, please apply it.
> But after all, it's a convention and for some cases there might be
> good reasons to deviate from the convention.
As usual with conventions.
But at least I don't see a good reason to deviate here.
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Index: src/algebra/matcat.spad.pamphlet
===================================================================
--- src/algebra/matcat.spad.pamphlet (revision 1501)
+++ src/algebra/matcat.spad.pamphlet (working copy)
@@ -280,8 +280,8 @@
minordet : % -> R
++ \spad{minordet(m)} computes the determinant of the matrix m using
++ minors. Error: if the matrix is not square.
- Pfaffian : % -> R
- ++ \spad{Pfaffian(m)} returns the Pfaffian of the matrix m.
+ pfaffian : % -> R
+ ++ \spad{pfaffian(m)} returns the Pfaffian of the matrix m.
++ Error: if the matrix is not antisymmetric.
if R has Field then
inverse : % -> Union(%,"failed")
@@ -845,29 +845,29 @@
The Pfaffian is the constant term of the \emph{Pfaffian-characteristic
polynomial}:
<<category MATCAT MatrixCategory>>=
- Pfaffian A ==
+ pfaffian A ==
if antisymmetric? A
then if odd? nrows A
then 0
else PfChar(A).0
- else error "Pfaffian: only defined for antisymmetric square matrices!"
+ else error "pfaffian: only defined for antisymmetric square matrices!"
@
<<TEST MATCAT>>=
-testcase "Pfaffian"
+testcase "pfaffian"
m n == matrix [[(if i = j then 0 _
else if i < j _
then x[i, j] _
else -x[j, i]) for i in 1..n] for j in 1..n]
-testEquals("Pfaffian [[0,1,0,0],[-1,0,0,0],[0,0,0,1],[0,0,-1,0]]", "1")
-testEquals("Pfaffian [[0, u, v, w],[-u, 0, x, y],[-v,-x,0,z],[-w,-y,-z,0]]", _
+testEquals("pfaffian [[0,1,0,0],[-1,0,0,0],[0,0,0,1],[0,0,-1,0]]", "1")
+testEquals("pfaffian [[0, u, v, w],[-u, 0, x, y],[-v,-x,0,z],[-w,-y,-z,0]]", _
"u*z-v*y+w*x")
-testEquals("Pfaffian m 3", "0")
-testEquals("Pfaffian [[0,0],[0,0]]", "0")
+testEquals("pfaffian m 3", "0")
+testEquals("pfaffian [[0,0],[0,0]]", "0")
M := m 6;
-testEquals("(Pfaffian M)^2", "determinant M")
-testLibraryError "Pfaffian [[1,2],[0,0]]"
-testLibraryError "Pfaffian [[1,2,3],[0,0,0]]"
+testEquals("(pfaffian M)^2", "determinant M")
+testLibraryError "pfaffian [[1,2],[0,0]]"
+testLibraryError "pfaffian [[1,2,3],[0,0,0]]"
@
@@ -1166,8 +1166,8 @@
minordet : % -> R
++ \spad{minordet(m)} computes the determinant of the matrix m
++ using minors.
- Pfaffian : % -> R
- ++ \spad{Pfaffian(m)} returns the Pfaffian of the matrix m.
+ pfaffian : % -> R
+ ++ \spad{pfaffian(m)} returns the Pfaffian of the matrix m.
++ Error: if the matrix is not antisymmetric.
if R has Field then
Index: src/algebra/matrix.spad.pamphlet
===================================================================
--- src/algebra/matrix.spad.pamphlet (revision 1501)
+++ src/algebra/matrix.spad.pamphlet (working copy)
@@ -441,7 +441,7 @@
determinant x == determinant(x pretend Matrix(R))
minordet x == minordet(x pretend Matrix(R))
- Pfaffian x == Pfaffian(x pretend Matrix(R))
+ pfaffian x == pfaffian(x pretend Matrix(R))
if R has EuclideanDomain then
