# Getting Error while using lambdify

**URL:** <https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956>\
**Category:** General Usage\
**Tags:** symbolics, sympy\
**Created:** [November 8, 2022, 10:54pm UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956 "2022-11-08T22:54:56Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Starpower\_Power](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/starpower_power/32/38282_2.png) [@Starpower\_Power](https://discourse.julialang.org/u/Starpower_Power)\
**Post date:** [November 8, 2022, 10:54pm UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956/1 "2022-11-08T22:54:56Z")

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![image](https://global.discourse-cdn.com/julialang/original/3X/b/3/b32379fbf44be564fed9c5665685c14a10e006b6.png)

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<div class="post-metadata">

**Author:** ![mzaffalon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mzaffalon/32/214168_2.png) [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Post date:** [November 9, 2022, 6:36am UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956/2 "2022-11-09T06:36:24Z")

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Could you please copy-paste text based code instead of a screenshot and possibly post a minimal (non-)working example?

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<div class="post-metadata">

**Author:** ![mzaffalon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mzaffalon/32/214168_2.png) [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Post date:** [November 9, 2022, 6:52am UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956/3 "2022-11-09T06:52:58Z")

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I see that you \theta\_1 is a function of `t`: you want \theta\_1 to be a `symbols` instead.  
I don’t know if you can `lambdify` using a function as an argument.

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<div class="post-metadata">

**Author:** ![Starpower\_Power](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/starpower_power/32/38282_2.png) [@Starpower\_Power](https://discourse.julialang.org/u/Starpower_Power)\
**Post date:** [November 11, 2022, 1:10pm UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956/4 "2022-11-11T13:10:03Z")

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```julia
using SymPy
using PyCall
sp = pyimport("sympy")
@vars t
x = sp.Function("x")(t)
y = sp.Function("y")(t)
z = x^2+y^2
hz = lambdify(z,(x,y))
hz(1,1)

```

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<div class="post-metadata">

**Author:** ![mzaffalon](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mzaffalon/32/214168_2.png) [@mzaffalon](https://discourse.julialang.org/u/mzaffalon)\
**Post date:** [November 11, 2022, 1:17pm UTC](https://discourse.julialang.org/t/getting-error-while-using-lambdify/89956/5 "2022-11-11T13:17:05Z")

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What do you expect the result of `hz(1,1)` to be? If you expect it to evaluate 1^2+1^2, then

```julia
using SymPy
@vars x y
z = x^2+y^2
hz = lambdify(z,(x,y))
hz(1,1)

```

Note that you do not need to import `sympy` directly and that `SymFunction` is also exposed:

```julia
using SymPy
@vars t
x = SymFunction("x")(t)
y = SymFunction("y")(t)
z = x^2+y^2

```