Singular Manual: isPositive

| #### D.15.12.34 isPositive Procedure from library `multigrading.lib` (see multigrading_lib). Usage: isPositive() Purpose: Computes whether the multigrading of the ring is positive. For computation theorem 8.6 of the Miller/Sturmfels book is used. Returns: true if the multigrading is positive Example:
    LIB "multigrading.lib";
    printlevel = 3;
    ring r = 0,(x,y),dp;
    intmat A[1][2]=-1,1;
    setBaseMultigrading(A);
    isPositive();
    ==>    ? Sorry: cannot find 'hilbert' command from 4ti2. Please install 4ti2!
    ==>    ? leaving multigrading.lib::hilbert4ti2intmat (0)
    ==>    ? leaving multigrading.lib::multiDegBasis (3317)
    ==>    ? leaving multigrading.lib::isPositive (4329)
    intmat B[1][2]=1,1;
    setBaseMultigrading(B);
    isPositive(B);
    ==>    ? Sorry: cannot find 'hilbert' command from 4ti2. Please install 4ti2!
    ==>    ? leaving multigrading.lib::hilbert4ti2intmat (0)
    ==>    ? leaving multigrading.lib::multiDegBasis (3317)
    ==>    ? leaving multigrading.lib::isPositive (4328)

User manual for Singular version 4.3.2, 2023, generated by texi2html.