CheckUnimodular -- optional input which gives the user the option to check whether the given matrix is unimodular

i1 : R = QQ[x,y]

o1 = R

o1 : PolynomialRing

i2 : f = matrix{{x^2*y+1,x+y-2,2*x*y}}

o2 = | x2y+1 x+y-2 2xy |

             1      3
o2 : Matrix R  <-- R

i3 : U = qsAlgorithm(f, CheckUnimodular => true)

o3 = | 1     2xy    -x-y+2        |
     | 0     0      1             |
     | -1/2x -x2y-1 1/2x2+1/2xy-x |

             3      3
o3 : Matrix R  <-- R

i4 : f*U

o4 = | 1 0 0 |

             1      3
o4 : Matrix R  <-- R