ValueError: setting an array element with a sequence.

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Gaël Grissonnanche

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May 1, 2020, 12:21:30 AM5/1/20
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Hi !

I just started playing with Symengine today for a "heavy" project I have. Replacing Sympy by Symengine did not work out of the box in my code. First, because the Lambidy-ed function from Symengine does not get "jit" in Numba, which a priori will become a problem for me. But it is not only that, after removing "jit", my code raised the following error:

ValueError: setting an array element with a sequence.

I made a simple example below that reproduces the problem. Sympy does not meet issue here, but Symengine raises an exception.
Do you know what is happening?

------------------------------------

import symengine as se
import sympy as sp
import numpy as np


x, y = se.var("x y")
expr = se.sin(x)*se.cos(y)
func = sp.lambdify((x,y), expr, 'numpy')
print(func(0, np.array([0,2])))

x, y = se.var("x y")
expr = se.sin(x)*se.cos(y)
func = se.Lambdify((x,y), expr)
print(func(np.pi/2, np.array([0, np.pi/2])))

------------------------------------

Thank you for your time and help!

Best,

Gaël

Isuru Fernando

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May 1, 2020, 3:39:30 PM5/1/20
to symengine
Hi,

Looks like this is a problem with broadcasting one input. For example, the following works,


import symengine as se
import sympy as sp
import numpy as np

x, y = se.var("x y")
expr = se.sin(x)*se.cos(y)
func = se.Lambdify((x,y), expr, backend='llvm')
print(func([np.pi/2, np.pi/2], np.array([0, np.pi/2])))

Btw, backend='llvm' should work the same as Numba. (except no implicit multi-core  support)

Isuru

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