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document {
Key => {
newCoordinateSystem,
(newCoordinateSystem, PolynomialRing, Matrix)
},
Headline => "change variables",
TT "newCoordinateSystem(S,m)", " -- takes a one-rowed matrix ", TT "m", " of
independent linear forms over a ring ", TT "R", " and returns a pair
", TT "(f,g)", ", where ", TT "f", " is a ring map given by some linear change
of coordinates from ", TT "R", " to ", TT "S", " which sends the last variables
of ", TT"R", " to the forms in ", TT "m", ", and ", TT "g", " is the inverse
of ", TT "f", ".",
PARA{},
"The ring ", TT "S", " should have the same number of variables as
", TT "S", ".",
EXAMPLE {
"R = ZZ/101[a..d]",
"S = ZZ/101[p..s]",
"(f,g) = newCoordinateSystem(S,matrix{{a+2*b,3*c-d}});",
"f",
"g"
},
}
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