theano_function unable to convert consecutive trigonometry multiplication

[extraymond]

System info:

• LIb: Sympy(1.1.1), theano(1.0.1) via conda-forge.
• Python: I'm using python 3.6
• OS: ubuntu 18.04

Problem:

I've tried to convert a matrix containing multiple trigonometry functions to theano_code by theano_function, this is what I've found:

1. when number of trig_function is less then 3, everything is fine.
   This will give generate a valid function.

function = theano_code([theta1, theta2], [cos(theta1) * sin(theta2)])

2. However, when consecutive multiplication happens, theano_function will raise error.
   This will not pass the code_gen:

function = theano_code([theta1, theta2], [cos(theta1) * sin(theta2)* cos(theta1])

And the error message:

Input 0 of the graph (indices start from 0), used to compute Elemwise{sin,no_inplace}(theta1_t), was not provided and not given a value.

I was wondering what cause this behavior, the temporary fix is to create a thin layer that take out part of the trigonometry variables out, but is a really messy solution IMO.

Thanks!