Erorr: SymFunction and @funs have not been defined about symengine.jl

[jverzani]

As far as I know, this feature is not in SymEngine, but it is in SymPy. In SymPy.jl you have the constructor SymFunction and macro @symfuns (called without a comma).

[nhannguyen123]

@jverzani . Thanks. After using SymPy, I can define the symbolic function f

using PyCall
using SymPy
@vars x y
f = SymFunction("f")

However, the next expression

f(x,y)

comes to error

PyError (:PyObject_Call) <class 'sympy.core.sympify.SympifyError'>
SympifyError()
  File "/usr/lib/python2.7/dist-packages/sympy/core/function.py", line 616, in __new__
    args = list(map(sympify, args))
  File "/usr/lib/python2.7/dist-packages/sympy/core/sympify.py", line 315, in sympify
    raise SympifyError('could not parse %r' % a, exc)


 in pyerr_check at /home/nhan/.julia/v0.5/PyCall/src/exception.jl:56 [inlined]
 in pyerr_check at /home/nhan/.julia/v0.5/PyCall/src/exception.jl:61 [inlined]
 in macro expansion at /home/nhan/.julia/v0.5/PyCall/src/exception.jl:81 [inlined]
 in #_pycall#66(::Array{Any,1}, ::Function, ::PyCall.PyObject, ::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:596
 in _pycall(::PyCall.PyObject, ::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:584
 in #pycall#70(::Array{Any,1}, ::Function, ::PyCall.PyObject, ::Type{PyCall.PyAny}, ::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:618
 in pycall(::PyCall.PyObject, ::Type{PyCall.PyAny}, ::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:618
 in #call#71(::Array{Any,1}, ::PyCall.PyObject, ::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:621
 in (::PyCall.PyObject)(::PyCall.PyObject, ::Vararg{PyCall.PyObject,N}) at /home/nhan/.julia/v0.5/PyCall/src/PyCall.jl:621
 in (::SymPy.SymFunction)(::SymEngine.Basic, ::SymEngine.Basic, ::Vararg{SymEngine.Basic,N}) at /home/nhan/.julia/v0.5/SymPy/src/call.jl:15

Could you explain this error? Sorry I'm a newbie in both Python and Julia.

[isuruf]

@nhannguyen123, following should work if you are using the latest version. What version of SymEngine are you using?

using SymEngine
@vars x y
f = SymFunction("f")
@funs g h

[jverzani]

Oops, sorry for the noise @nhannguyen123 and @isuruf . I grepped through a stale version of SymEngine before answering.

[isuruf]

Ah, it seems you need SymEngine master for this. I'll make a release in a few hours.

Oops, sorry for the noise @nhannguyen123 and @isuruf . I grepped through a stale version of SymEngine before answering.

np

[nhannguyen123]

@isuruf The versions that I'm using are

PyCall	1.14.0
SymEngine	0.2.0
SymPy	0.5.3
As I have said, after using SymPy I can defined f, g, h as follows

using PyCall
using SymPy
@vars x y
f = SymFunction("f")
@symfuns g h # note that: @funs --> error

However the following code makes error

f(x,y)

If it's because the module I'm using is not the latest, then I will wait for the new release. Thanks.

[isuruf]

SymPy and SymEngine can't interoperate. So you should use either SymPy or SymEngine, not both.

For me, following works. If it doesn't please open an issue at https://github.com/JuliaPy/SymPy.jl

using PyCall
using SymPy
@vars x y
f = SymFunction("f")
@symfuns g h 
f(x,y)

If you want to use SymEngine, you can do

Pkg.checkout("SymEngine")
Pkg.build("SymEngine")

to use the git master. After doing that, you can do,

using SymEngine
@vars x y
f = SymFunction("f")
@funs g h
f(x,y)

[nhannguyen123]

@isuruf @jverzani Thank you. @SymFunction and @funs in SymEngine work now.