Wrong order in diophantine() with syms

[boyoungzheng]

In diophantine.py line 488--490

dict_sym_index = dict(zip(syms, range(len(syms))))
return {tuple([t[dict_sym_index[i]] for i in var])
            for t in diophantine(eq, param, permute=permute)}

I think we should switch syms and var here. We want returns in the order of syms rather than var. Otherwise, it makes no sense to me. So it should be

dict_var_index = dict(zip(var, range(len(var))))
return {tuple([t[dict_var_index[i]] for i in syms])
            for t in diophantine(eq, param, permute=permute)}

[oscarbenjamin]

Can you give examples of how the output from diophantine would be different?

[boyoungzheng]

>>> diophantine(x1+2*x2+3*x3)
{(t_0, t_0 + 3*t_1, -t_0 - 2*t_1)}
>>> diophantine(x1+2*x2+3*x3, syms=[x3, x1, x2])
{(t_0 + 3*t_1, -t_0 - 2*t_1, t_0)}

After the code modification

>>> diophantine(x1+2*x2+3*x3)
{(t_0, t_0 + 3*t_1, -t_0 - 2*t_1)}
>>> diophantine(x1+2*x2+3*x3, syms=[x3, x1, x2])
{(-t_0 - 2*t_1, t_0, t_0 + 3*t_1)}