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D.5.4.4 negativedivisor
Procedure from librarydivisors.lib (see divisors_lib).
- Usage:
- negativedivisor(A); A*(-1); A = divisor.
- Assume:
- A is a divisor on X.
- Return:
- a divisor on X
- Theory:
- The procedure will interchange the numerator and denominator ideals.
LIB "divisors.lib"; ring r=31991,(x,y,z),dp; ideal I = y^2*z - x*(x-z)*(x+3*z); qring Q = std(I); divisor A = makeDivisor(ideal(x,z),ideal(1)); A; ==> (z,x) - (1) ==> divisor D = negativedivisor(A); D; ==> (1) - (z,x) ==> |