check(MultirationalMap) -- check that a multi-rational map is well-defined

Synopsis

Function: check
Usage:

check Phi
Inputs:
- a multi-rational map
Optional inputs:
- UserMode => ..., default value null,
- Verbose => ..., default value false,
Outputs:
- a multi-rational map, the same object passed as input, but an error is thrown if the target of the map is not compatible.

i1 : f = rationalMap ideal PP_(ZZ/65521)^(1,4);

o1 : RationalMap (quadratic rational map from PP^4 to PP^5)

i2 : Phi = rationalMap {f}

o2 = Phi

o2 : MultirationalMap (rational map from PP^4 to PP^5)

i3 : check Phi

o3 = Phi

o3 : MultirationalMap (rational map from PP^4 to PP^5)

i4 : Y = image Phi

o4 = Y

o4 : ProjectiveVariety, hypersurface in PP^5

i5 : Psi = rationalMap({f},Y)

o5 = Psi

o5 : MultirationalMap (rational map from PP^4 to Y)

i6 : check Psi

o6 = Psi

o6 : MultirationalMap (rational map from PP^4 to Y)

i7 : p = point Y;

o7 : ProjectiveVariety, a point in PP^5

i8 : Eta = rationalMap({f},p);

o8 : MultirationalMap (rational map from PP^4 to p)

i9 : stopIfError = false;

i10 : check Eta
stdio:10:5:(3): error: the target variety is not compatible with the maps