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Divisor :: toWeilDivisor

toWeilDivisor -- create a Weil divisor from a Q or R-divisor

Synopsis

Description

Given a divisor with rational or real coefficients, but whose coefficients are actually integers, we first check if all coefficients are integers. If so we make this divisor to a Weil divisor. Otherwise, an error is thrown.

i1 : R=QQ[x];
i2 : D=divisor({3/2}, {ideal(x)}, CoeffType=>QQ)

o2 = 3/2*Div(x)

o2 : QWeilDivisor on R
i3 : E=divisor({1.5}, {ideal(x)}, CoeffType=>RR)

o3 = 1.5*Div(x)

o3 : RWeilDivisor on R
i4 : toWeilDivisor(2*D)

o4 = 3*Div(x)

o4 : WeilDivisor on R
i5 : toWeilDivisor(2*E)

o5 = 3*Div(x)

o5 : WeilDivisor on R
i6 : isWeilDivisor(D)

o6 = false
i7 : try toWeilDivisor(D) then print "converted to a WeilDivisor" else print "can't be converted to a WeilDivisor"
can't be converted to a WeilDivisor

Notice in the final computation, D cannot be converted into a Weil divisor since D has non-integer coefficients, but 2*D can be converted into a Weil divisor.

See also

Ways to use toWeilDivisor :