error multiplying matrices with entries in fraction field

[pzinn]

am I the only one encountering such issues?...

i1 : F=frac(QQ[y])

o1 = F

o1 : FractionField

i2 : a=matrix{{1/2}}*matrix{{y}}

o2 = | 1/2y |

             1      1
o2 : Matrix F  <-- F

i3 : b=matrix{{y/2}}

o3 = | y/2 |

             1      1
o3 : Matrix F  <-- F

i4 : a==b

o4 = false

i5 : a_(0,0)===b_(0,0)

o5 = false

i6 : ring a===ring b

o6 = true

i7 : source a===source b

o7 = true

i8 : target a===target b

o8 = true

i9 : a-b==0

o9 = true

[pzinn]

I can easily fix this but first there are some choices to make. One could say here that there are two possible problems:

• the equality failed because entries chose two different forms for fractions -- so the issue is, lack of a canonical form for fractions
• the equality failed because it's too strict: equality between fractions a/b==c/d should be about ad==bc but right now testing at the c level checks hashes, so is strict a==c and b==d

not sure if we should fix one, or both, of these issues

[mahrud]

A quick workaround is a-b==0, which tells me that the engine has the technical ability to check equality correctly.

i1 : F=frac(QQ[y])

o1 = F

o1 : FractionField

i2 : a=matrix{{1/2}}*matrix{{y}}

o2 = | 1/2y |

             1      1
o2 : Matrix F  <-- F

i3 : b=matrix{{y/2}}

o3 = | y/2 |

             1      1
o3 : Matrix F  <-- F

i4 : a-b==0

o4 = true

i5 : a-b

[mahrud]

Oh sorry, I just saw that you very last line is a-b==0 already, I did not read that far, never mind!