Looks like in lambdify one of the checks for dummification is broken. I'll open a PR in a minute here.
The dummification was only supposed to happen on numerical translation though, so modules='sympy' won't be fixed (or dictionaries). I don't know whether lambdify should always dummify or not though. -Gilbert On Sunday, September 1, 2013 9:45:18 AM UTC-7, Jason Moore wrote: > > Matthew, > > This is definitely a bug. We should report in the ticketing system. > > The lines here: > https://github.com/sympy/sympy/blob/master/sympy/utilities/lambdify.py#L279don't > make a lot of sense to me. I'm not sure why the dummify is set to > True only under those specific conditions. > > If dummify is overridden to always be true, the function seems to work as > expected. > > Gilbert Gede made those changes. Maybe he will chime in as to why the code > is as it is. I'll look into some fixes and some more tests too. > > > Jason > moorepants.info > +01 530-601-9791 > > > On Sat, Aug 31, 2013 at 5:45 PM, Matthew Brett > <matthe...@gmail.com<javascript:> > > wrote: > >> Hi, >> >> I was trying to debug a problem I was having with lambdify, and I got >> stuck trying to understand the newish 'dummify' changes. >> >> So, it's nice that this works now: >> >> from sympy import symbols, lambdify, sin >> from sympy.utilities.lambdify import implemented_function >> >> t = symbols('t') >> x = sin >> y = x(t) >> f = lambdify(y, 2*y, modules=None) >> # Evaluates OK >> print(f(0)) >> >> But I'm not sure why this should not also work: >> >> f = lambdify(y, 2*y, modules='sympy') >> # Error evaluating lambda >> print(f(0)) >> >> In order for this to work, I believe the 'dummify' parameter to >> 'lambdastr' has to be set to True from the call in 'lambdify', but >> this only happens if the strings 'numpy', 'math' or 'mpmath' appear >> first in the module list. For example these also fail: >> >> f = lambdify(y, 2*y, modules=numpy) >> f = lambdify(y, 2*y, modules=dict(sin=math.sin)) >> x = implemented_function('x', lambda x : x + 1) >> y = x(t) >> f = lambdify(y, 2*y, modules='sympy') >> >> Is it easy to explain why these should not work? >> >> Thanks a lot, >> >> Matthew >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sympy+un...@googlegroups.com <javascript:>. >> To post to this group, send email to sy...@googlegroups.com <javascript:> >> . >> Visit this group at http://groups.google.com/group/sympy. >> For more options, visit https://groups.google.com/groups/opt_out. >> > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. For more options, visit https://groups.google.com/groups/opt_out.
