expression(ToricDivisor) -- get the expression used to format for printing

Synopsis

Function: expression
Usage:

expression D
Inputs:
- D, a toric divisor,
Outputs:
- an expression, used to format D for printing

Description

This method is the primary function called upon by << to format for printing. It assumes that D is well-defined.

When the underlying normal toric variety has not been assigned a global variable, the $i$-th irreducible torus-invariant Weil divisor is displayed as $D_i$. However, if the underlying normal toric variety has been assigned a global variable $X$, the $i$-th irreducible torus-invariant Weil divisor is displayed as $X_i$. In either case, an arbitrary torus-invariant Weil divisor is displayed as an integral linear combination of these expressions.

i1 : toricDivisor({2,-7,3}, toricProjectiveSpace 2)

o1 = 2*D  - 7*D  + 3*D
        0      1      2

o1 : ToricDivisor on normalToricVariety ({{-1, -1}, {1, 0}, {0, 1}}, {{0, 1}, {0, 2}, {1, 2}})

i2 : toricDivisor convexHull (id_(ZZ^3) | - id_(ZZ^3))

o2 = D  + D  + D  + D  + D  + D  + D  + D
      0    1    2    3    4    5    6    7

o2 : ToricDivisor on normalToricVariety ({{1, 1, 1}, {-1, 1, 1}, {1, -1, 1}, {-1, -1, 1}, {1, 1, -1}, {-1, 1, -1}, {1, -1, -1}, {-1, -1, -1}}, {{0, 1, 2, 3}, {0, 1, 4, 5}, {0, 2, 4, 6}, {1, 3, 5, 7}, {2, 3, 6, 7}, {4, 5, 6, 7}})

i3 : PP2 = toricProjectiveSpace 2;

i4 : D1 = toricDivisor({2,-7,3}, PP2)

o4 = 2*PP2  - 7*PP2  + 3*PP2
          0        1        2

o4 : ToricDivisor on PP2

i5 : D2 = 2 * PP2_0 - 7 * PP2_1 + 3 * PP2_2

o5 = 2*PP2  - 7*PP2  + 3*PP2
          0        1        2

o5 : ToricDivisor on PP2

i6 : assert(D1 == D1)

Ways to use this method: