A workaround is to use unit_step instead of heaviside: plot3d(unit_step(x-y),(x,-1,1),(y,-1,1))
The function heaviside is known to have issues as soon as some numerical evaluation is required. Another example is: numerical_integral(heaviside(x), -1, 1) TypeError: unable to simplify to float approximation numerical_integral(unit_step(x), -1, 1) (1.0, 1.1102230246251565e-14) Best wishes, Eric. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.