It seems that, unfortunately, the information of whether or not a variable
is an IndexedBase object is discarded when using it in an expression. Check
```
from sympy import *
u = IndexedBase('u')
k = Symbol('k')
y = u[k]
print(isinstance(u, IndexedBase))
for s in y.free_symbols:
print(s, isinstance(s, IndexedBase))
```
Hm...
On Thursday, April 14, 2016 at 8:59:46 AM UTC+2, Nico Schlömer wrote:
>
> From an object like `sin(u[k]) + u0[k]` I would like to get the
> corresponding C code as a string. Since `k` is a variable, I cannot use
> `MatrixSymbol`, but there's always `IndexedBase` of course. With
> ```
> u = IndexedBase('u')
> u0 = IndexedBase('u0')
> k = Symbol('k')
> y = sin(u[k]) + u0[k]
> ```
> things are looking good, but then
> ```
> from sympy.utilities.codegen import codegen
> [(c_name, c_code), (h_name, c_header)] = codegen(("f", y), "C")
> ```
> tells you
> ```
> sympy.tensor.indexed.IndexException:
> Range is not defined for all indices in: u[k]
> ```
> I could perhaps go through all `IndexedBase` instances in `y` and
> `.subs`titute them with a variable with the string `u[k]`, but that feels
> hackish.
>
> Any hints?
>
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