fricas
)abbrev domain CMAP CellMap
++
CellMap(R,n) : Exports == Implementation where
R: Join(Ring,Comparable)
n: NonNegativeInteger
X ==> Expression R
DP ==> DirectProduct
OF ==> OutputForm
NNI ==> NonNegativeInteger
MAP ==> List X -> List X
DOM ==> List(Segment X)
Exports == Join(CoercibleTo OF,SetCategory,Evalable X) with
_= : (%,%) -> Boolean
++ f1=f2 checks if two given cell maps are equal, that is if they have
++ the same domain D and the same mapping from D into X^n.
cellMap : (DOM,MAP) -> %
++ cellMap(D,f) is the constructor. Usually one has to specify the
++ dimension of the target space. For example, let Q=[a..b,c..d], then
++ cellMap(Q,Z+->[sin(Z.1),cos(Z.2),Z.1*Z.2])$CMAP(INT,3) defines a
++ 2-surface in X^3.
getDom : % -> DOM
++ getDom(f) extracts the domain of f.
getMap : % -> MAP
++ getMap(f) extracts the map of f.
faces : % -> List List(%)
++ faces(f) returns the faces of f, that means the images of the boundary
++ of the domain. Note: the returned list contains pairs of faces
++ corresponding to the endpoints of intervals.
coords : (Symbol,PositiveInteger) -> List X
++ coords(s,m) provides a sample of coordinates s[1],..,s[m] as a list.
coordSymbols : (Symbol,PositiveInteger) -> List Symbol
++ coordSymbols(s,m) provides a sample of coordinates s[1],..,s[m] as a
++ list of symbols.
jacobianMatrix : % -> (List X -> Matrix X)
++ jacobianMatrix(f) returns the Jacobian matrix as a marix valued
++ function defined on the same cell as the cellMap.
tangentSpace : % -> (List(X) -> List(Vector X))
++ tangentSpace(f) returns a
coerce : % -> OutputForm
++ coerce(f) gives the output representation.
Implementation == add
Rep := Record(d:DOM,f:MAP)
(x:% = y:%):Boolean ==
l:NNI:=min(#(x.d),#(y.d))
v:List X
for j in 1..l repeat
s:X:=subscript('z,[j::OF])::X
v:=concat(v,s::X)
x.d =y.d and (x.f) v = (y.f) v => true
false
cellMap(dd:DOM,ff:MAP):% ==
#dd > n => error concat("#DOM > ",string n)
v:List X:=[1::X for j in 1..#dd]
~test(#ff(v)=n) => error concat("#Range ~= ", string n)
construct(dd,ff)
faceLoHi(x:%,i:NNI,lo:Boolean):% ==
l:NNI:=#(x.d)
v:List X
for j in 1..l repeat
if j=i then
if lo then
s:X:=lo(x.d.i)
else
s:X:=hi(x.d.i)
else
if j>i then
s:X:=subscript('%,[(j-1)::OF])::X
else
s:X:=subscript('%,[j::OF])::X
v:=concat(v,s::X)
vv:=delete(v,i..i)
dd:List(Segment X):=delete(x.d,i..i)
ff:MAP:=vv+->(x.f) v
cellMap(dd,ff)
faces(x:%):List List(%) ==
l:NNI:=#(x.d)
[[faceLoHi(x,j,true), faceLoHi(x,j,false)] for j in 1..l]
getDom(x) == x.d
getMap(x) == x.f
coordSymbols(s:Symbol,m:PositiveInteger):List Symbol ==
[subscript(s,[j::OF]) for j in 1..m]
coords(s:Symbol,m:PositiveInteger):List X ==
xs:=[subscript(s,[j::OF]) for j in 1..m]
[coerce(xs.j)$X for j in 1..#xs]
jacobianMatrix(S:%):List(X) -> Matrix(X) ==
--xs:List Symbol:=v:=[subscript('x,[j::OF]) for j in 1..#(getDom S)]
--x:List X:=[coerce(xs.j)$X for j in 1..#xs]
xs:List Symbol:=coordSymbols('x,#(getDom S)::PositiveInteger)
x:List X:=coords('x,#xs::PositiveInteger)
F:List X:=(getMap S) x
J:Matrix(X):=matrix [[D(ff,u) for u in xs] for ff in F]
if Matrix(X) has Join(SetCategory,Evalable(X)) then
(y:List X):Matrix(X)+-> eval(J,x,y)
else
(y:List X):Matrix(X)+-> J
tangentSpace(S:%):List(X) -> List(Vector X) ==
J:=jacobianMatrix(S)
x:List X:=coords('x,#(getDom S)::PositiveInteger)
if Vector(X) has Join(SetCategory,Evalable(X)) then
if X has EuclideanDomain then
cs:List(Vector X):=columnSpace(J x)
(y:List X):List Vector(X)+-> [eval(t,x,y) for t in cs]
coerce(x) ==
v:List X
for j in 1..#(x.d) repeat
s:X:=subscript('%,[j::OF])::X
v:=concat(v,s::X)
r:List X:=(x.f) v
hconcat ["|",x.d::OF," -> ",r::OF,"|"]
fricas
)abbrev domain SCMPLX SurfaceComplex
++
SurfaceComplex(R,n) : Exports == Implementation where
NNI ==> NonNegativeInteger
INT ==> Integer
n : NNI
R : Join(Ring,Comparable)
CMAP ==> CellMap(R,n)
CTOF ==> CoercibleTo OutputForm
X ==> Expression R
OF ==> OutputForm
MAP ==> List X -> List X
DOM ==> List(Segment X)
Exports == Join(AbelianGroup ,CTOF, RetractableTo CMAP) with
bdry : % -> %
++ bdry(S) computes the boundary of the surface complex S.
size : % -> NNI
++ size(S) returns the number of "pieces" of the surface complex S.
nthCoef : (%,Integer) -> Integer
++ nthCoef(x, n) returns the coefficient of the n^th term of x.
nthFactor : (%,Integer) -> CMAP
++ nthFactor(x, n) returns the factor of the n^th term of x.
zero? : % -> Boolean
++ zero?(S) returns true if S is the empty surface complex.
_= : (%,%) -> Boolean
++ S=S' checks if the surface complexes S and S' are equal.
terms : % -> List(Record(gen: CMAP,exp: Integer))
++ terms(S) returns all terms of S as a record.
mapGen : ((CMAP -> CMAP),%) -> %
++ mapGen(f, e1 a1 +...+ en an) returns
++ \spad{e1 f(a1) +...+ en f(an)}.
mapCoef : ((Integer -> Integer),%) -> %
++ mapCoef(f, e1 a1 +...+ en an) returns
++ \spad{f(e1) a1 +...+ f(en) an}.
construct : (DOM,MAP) -> %
++ construct(d,f) constructs a term (piece) of a k-surface, where
++ d is the domain (a k-cell) and f is a mapping from d to a vector
++ space of dimension n.
--coerce : % -> OutputForm
Implementation == FreeAbelianGroup(CMAP) add
Rep:=FreeAbelianGroup(CMAP)
bdry(c:%):% ==
if size(c) = 1 then
s:=nthFactor(c,1)
l:=faces(s)
fs:=[(a.2::Rep-a.1::Rep) for a in l]
sgn:=(j:INT):INT+->if even? (j-1) then 1 else -1
nthCoef(c,1)*reduce("+",[sgn(j)*fs.j::Rep for j in 1..#fs])
else
ct:=[(nthCoef(c,j)*nthFactor(c,j))::Rep for j in 1..size(c)]
reduce("+",map(bdry,ct))
construct(d:DOM,f:MAP):% == cellMap(d,f)$CMAP::%
fricas
Compiling FriCAS source code from file
/var/lib/zope2.10/instance/axiom-wiki/var/LatexWiki/9220523246559970704-25px.001.spad
using old system compiler.
CMAP abbreviates domain CellMap
------------------------------------------------------------------------
initializing NRLIB CMAP for CellMap
compiling into NRLIB CMAP
****** Domain: R already in scope
compiling exported = : ($,$) -> Boolean
Time: 0.09 SEC.
compiling exported cellMap : (List Segment Expression R,List Expression R -> List Expression R) -> $
Time: 0.02 SEC.
compiling local faceLoHi : ($,NonNegativeInteger,Boolean) -> $
****** comp fails at level 9 with expression: ******
error in function faceLoHi
(SEQ (|:=| (|:| |l| (|NonNegativeInteger|)) (|#| (|x| |d|)))
(|:| |v| (|List| (|Expression| R)))
(REPEAT (IN |j| (SEGMENT 1 |l|))
(SEQ
(IF (= |j| |i|)
(IF |lo|
(|:=| (|:| |s| (|Expression| R)) (|lo| ((|x| |d|) |i|)))
(|:=| (|:| |s| (|Expression| R)) (|hi| ((|x| |d|) |i|))))
(IF (> |j| |i|)
(|:=| (|:| |s| (|Expression| R))
(|::|
(|subscript| '$
(|construct| (|::| (- |j| 1) (|OutputForm|))))
(|Expression| R)))
(|:=| (|:| |s| (|Expression| R))
(|::|
(|subscript| '$
(|construct| (|::| |j| (|OutputForm|))))
(|Expression| R)))))
(|exit| 1
(|:=| |v| (|concat| |v| (|::| |s| (|Expression| R)))))))
(|:=| |vv| (|delete| |v| (SEGMENT |i| |i|)))
(|:=| (|:| |dd| (|List| (|Segment| (|Expression| R))))
(|delete| (|x| |d|) (SEGMENT |i| |i|)))
(|:=|
(|:| |ff|
(|Mapping| (|List| (|Expression| R)) (|List| (|Expression| R))))
(+-> |vv| ((|x| |f|) |v|)))
(|exit| 1 (|cellMap| |dd| |ff|)))
****** level 9 ******
$x:= lo
$m:= $
$f:=
((((|s| #) (|j| # #) (|v| #) (|l| # #) ...)))
>> Apparent user error:
Cannot coerce lo
of mode (Boolean)
to mode (Record (: d (List (Segment (Expression R)))) (: f (Mapping (List (Expression R)) (List (Expression R)))))fricas
)clear all
All user variables and function definitions have been cleared.
R ==> EXPR INT
Type: Void
fricas
OF ==> OutputForm
Type: Void
fricas
-- Cell map
R2 ==> CellMap(INT,2)
Type: Void
fricas
R3 ==> CellMap(INT,3)
Type: Void
fricas
R4 ==> CellMap(INT,4)
Type: Void
fricas
Q2 ==> [0..1,0..1::R]
Type: Void
fricas
Q3 ==> concat(Q2,[0..1::R])
Type: Void
fricas
--xs:List Symbol:=coordSymbols('x,4)$R4
----------------------------------------------------------------
-- https://en.wikipedia.org/wiki/Jacobian_matrix_and_determinant
----------------------------------------------------------------
-- Example 1
F1:=cellMap(Q2,X+->[X.1^2*X.2,5*X.1+sin(X.2)])$R2
CellMap is an unknown constructor and so is unavailable. Did you
mean to use -> but type something different instead?