id summary reporter owner description type status priority milestone component resolution keywords cc merged author reviewer upstream work_issues branch commit dependencies stopgaps
23376 Equality testing of genera of quadratic forms over ZZ changes the genus and produces false results sbrandhorst "{{{
sage: D4 = QuadraticForm(Matrix(ZZ,4,4,[2,0,0,-1,0,2,0,-1,0,0,2,-1,-1,-1,-1,2]))
sage: G = D4.global_genus_symbol()
sage: sage.quadratic_forms.genera.genus.is_GlobalGenus(G)
True
sage: G == copy(G)
True
sage: sage.quadratic_forms.genera.genus.is_GlobalGenus(G)
False
}}}
The reason is that various functions unintentionally modify their input. Since a genus consists of lists containing lists, functions do just copy the lists but not deepcopy.
For example sage.quadratic_forms.genera.genus.canonical_2_adic_reduction modifies its input which does not seem to be intended." defect closed major sage-8.0 quadratic forms fixed sd87, Genus, sd91 Simon Brandhorst Anthony Várilly-Alvarado, Jen Berg N/A 24a5b0bcc3f31e1dcf08ce88c0c709578a8bbf7c