Report Bugs on This Page

From Snowbird
Jump to: navigation, search

Please Report Bugs on this page. Include your initials, brief explanation, and a clear example that produces the bug

AT: rank of a module seems to only work for singly graded modules
S = ZZ/101[x_1,x_2, Degrees => {{1,1}, {1,-3}}]
I = ideal(x_1^4*x_2^3)
f = matrix{{x_1,x_2, 0, 0, 0}, {0, 0 , x_1^2, x_1*x_2, x_2^2}}
F = map(S^{{-2, 1}, {2, 2}}, S^{{-3, 0},{ -3, 4},{0,0}, {0, 4}, {0,8}}, f)
R = S/I
M = (image F)**R
rank M




===========

AS,AO,DR: Is it meant that "presentation" returns a Matrix whereas "minimalPresentation" returns a Module?

DG: Oops, a much better name would have been "minimizePresentation", sorry! Please use the synonym "prune", instead. Would it be okay if in the next version of Macaulay 2 we rename the function, provided "minimalPresentation", when used, says something like "'minimalPresentation' has been replaced by 'minimizePresentation'"?

===========

AHH: SimpleDoc Inputs that are optional arguments show up under the regular inputs.

===========

Help! When I try installPackage "Foo", it the examples, when run, give error messages about the SimpleDoc.m2 not being found, but I already installed it.

Workaround: use installPackage("Foo", UserMode => true) instead.

In the next version of Macaulay2, the default value for this option will be false.

Explanation: when UserMode is set to false, that means that M2 is started up to run the examples with the "-q" option, which specifies that M2 should not look in the Macaulay 2 application directory under the user's home directory for packages the user may have installed previously.


===========

DR: bug concerning degrees of target module

  • R = QQ[x,y,z]
  • r1 = res cokernel matrix { { x,y,z } }
  • complete r1
  • r2 = res cokernel matrix { { x^2+y^2, y^3+z^3 } }
  • complete r2
  • rr = r1 ** r2
  • M = (rr.dd_3)^{0,1,2}
  • target M

seems to forget the degrees...


Related with this effect may also be the following:

  • S = QQ[x,y]
  • M1 = map(S^{-1,-2,-3}, S^{-1,-1,-1}, {{1,0,0},{0,1,0},{0,0,1}})
  • degrees image M1

results in {{1}, {1}, {1}}

===========