# Problems in use symbolic math

**URL:** <https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957>\
**Category:** General Usage\
**Created:** [August 14, 2020, 8:06pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957 "2020-08-14T20:06:57Z")\
**Posts on this page:** 20\
**Page:** 1

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 14, 2020, 8:06pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/1 "2020-08-14T20:06:57Z")

</div>

I am trying to use SymPy package to deal with symbolic math. For example:

```julia
using SymPy
x, y, z = symbols("x y z")
z=(x^2+y^2)/(y^2+1);

```

However, the error appears:

```julia
x, y, z = symbols("x y z")
ERROR: ArgumentError: ref of NULL PyObject

```

Anyone can help me please?

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 14, 2020, 8:12pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/2 "2020-08-14T20:12:54Z")

</div>

Working for me:

```julia
               _
   _ _ _(_)_ | Documentation: https://docs.julialang.org
  (_) | (_) (_) |
   _ _ _| |_ __ _ | Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` | |
  | | |_| | | | (_| | | Version 1.5.0 (2020-08-01)
 _/ |\ __'_|_|_|\__'_| | Official https://julialang.org/ release
|__/ |

julia> using SymPy

julia> x, y, z = symbols("x y z")
(x, y, z)

julia> z=(x^2+y^2)/(y^2+1)
 2 2
x + y 
───────
  2    
 y + 1

```

Perhaps your Python installation is broken?  
Operating system?  
Are you using Conda?

Citation:

To force Julia to use its own Python distribution, via Conda, simply set `ENV["PYTHON"]` to the empty string `""` and re-run `Pkg.build("PyCall")` .

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 14, 2020, 8:23pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/3 "2020-08-14T20:23:25Z")

</div>

> [@ufechner7](#):
>
> ENV[“PYTHON”]

I am with windows  
Julia version 1.0.4  
I re run Pkg.build(“PyCall”) but nothing yet!  
Can I remove all packages and reinstall all?

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 14, 2020, 8:37pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/4 "2020-08-14T20:37:29Z")

</div>

We have updated but nothing work:

 ![ruim](https://global.discourse-cdn.com/julialang/original/3X/c/c/cc228abb1e37969e1ddabee16e3854b964cf2652.png)

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 14, 2020, 11:22pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/5 "2020-08-14T23:22:04Z")

</div>

Did you execute:

> [@ufechner7](#):
>
> `ENV["PYTHON"]`=“”

before executing  
`Pkg.build("PyCall")`

That is important.

Furthermore, if it is possible for you, install Julia 1.5 instead of 1.0.4 . It works much more smoothly.

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 12:42am UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/6 "2020-08-15T00:42:09Z")

</div>

Nothing yet…  
See:

 ![ruim](https://global.discourse-cdn.com/julialang/original/3X/7/7/771ff4f7daf7f0bbfb5df6ac8a945f1840c52859.png)  
Could you help me please? Is the version 1.0.4?  
I have afraid to other packages and many sintaxes change when I use the version 1.5.

---

<div class="post-metadata">

**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [August 15, 2020, 1:10am UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/7 "2020-08-15T01:10:16Z")

</div>

It should be possible to run any code that works with 1.0.4 on 1.5.  
But note that you can install version 1.5 at the same time as 1.0.4 and choose which version you want to run.

Version 1.5 has a lot of advantages, and packages (that are maintained) are probably more likely to work correctly.

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 15, 2020, 1:13am UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/8 "2020-08-15T01:13:19Z")

</div>

Please execute:

```julia
ENV["PYTHON"]=""
Pkg.build("PyCall")

```

You did it in the wrong order.

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 2:17pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/9 "2020-08-15T14:17:49Z")

</div>

Dear friend,  
I did as you told me; installed version 1.5 and ran ENV[“PYTHON”]=“” and then Pkg.build(“PyCall”).  
But nothing happens, it stays for hours “installing”.  
Do you know what this could be, please?

 ![image](https://global.discourse-cdn.com/julialang/original/3X/9/d/9d2c2ead5e7aa0e4640f726b80747f9028294fcf.png)

---

<div class="post-metadata">

**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [August 15, 2020, 2:38pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/10 "2020-08-15T14:38:44Z")

</div>

Did you try first just adding and running the `SymPy` package?

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 2:45pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/11 "2020-08-15T14:45:03Z")

</div>

Yes, but the error message appears: I don know how can I do…

 ![image](https://global.discourse-cdn.com/julialang/original/3X/f/6/f67f5e52c8206a10359aa4585da8878d2f0ee009.png)

---

<div class="post-metadata">

**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [August 15, 2020, 2:57pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/12 "2020-08-15T14:57:54Z")

</div>

Please try with Julia instead of JuliaPro

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 15, 2020, 2:58pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/13 "2020-08-15T14:58:35Z")

</div>

Yes, it can take a long amount of time.  
But you can see the progress by looking at the logfile:  
c:\Users\Usuario.julia\packages\PyCall\zqDXB\deps\build.log  
I guess I spelled your user name wrong, it seams to have special characters in it.

Not sure how to look at a log file in windows, in linux you just do:  
`tail -f <logfilename>`

Perhaps you can try to open the log file with your favorite editor.

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 3:38pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/14 "2020-08-15T15:38:27Z")

</div>

Special chacters avoid anything?

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 3:39pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/15 "2020-08-15T15:39:17Z")

</div>

I’ve installed all again. I’ll try to install now. Thank you so much

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 4:31pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/16 "2020-08-15T16:31:56Z")

</div>

Dear friend, you are on time at this very stage  
Nothing happens.

 ![image](https://global.discourse-cdn.com/julialang/original/3X/6/8/68a3925c205ea993cf2c5951cc832b19be8a6c3d.png)

---

<div class="post-metadata">

**Author:** ![ufechner7](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ufechner7/32/51363_2.png) [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Post date:** [August 15, 2020, 6:57pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/17 "2020-08-15T18:57:20Z")

</div>

Are you using Atom?  
Try to avoid that if you are debugging a problem, because it introduces addtional problems.

Did you:

1. install Julia 1.5 from [Download Julia](https://julialang.org/downloads/)
2. on the julia command prompt entered  
ENV[“PYTHON”]=“”

```julia
3. entered the package manager by pressing ]
4. run the command "up" to update the list of the packages
5. installed SymPy with the command
   add SymPy

Did any of these steps result in an error?

If yes, are you perhaps behind a firewall?

Furthermore, what is the output of the command
status
while you are in the package manager?

For me I have the output:
(@v1.5) pkg> status
Status `~/.julia/environments/v1.5/Project.toml`
  [6e4b80f9] BenchmarkTools v0.5.0
  [336ed68f] CSV v0.7.7
  [d749ddd5] DaemonMode v0.1.0 `https://github.com/dmolina/DaemonMode.jl#master`
  [a93c6f00] DataFrames v0.21.6
  [d330b81b] PyPlot v2.9.0
  [2db162a6] QML v0.6.0
  [24249f21] SymPy v1.0.27

(@v1.5) pkg> 
It will be different for you, but might be important to know.
```

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 7:08pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/18 "2020-08-15T19:08:27Z")

</div>

> [@ufechner7](#):
>
> `It will be different for you, but might be important to know.`

Dear Friend,  
I did all steps, all right.  
Could you see for me please and the next step?

 ![image](https://global.discourse-cdn.com/julialang/original/3X/4/c/4c5051c4a360590fa7c7e9fdbf734c1da306c16e.png)

---

<div class="post-metadata">

**Author:** ![dpsanders](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/dpsanders/32/3573_2.png) [@dpsanders](https://discourse.julialang.org/u/dpsanders)\
**Post date:** [August 15, 2020, 7:22pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/19 "2020-08-15T19:22:25Z")

</div>

Now press backspace and then

```julia
julia> using SymPy

```

But you did not follow the instructions to download the standard version of Julia from the download page pointed to by @ufechner7. You are still using Julia Pro, which is a different version that most people here are not familiar with.

---

<div class="post-metadata">

**Author:** ![angeloaliano1](https://avatars.discourse-cdn.com/v4/letter/a/7ea924/32.png) [@angeloaliano1](https://discourse.julialang.org/u/angeloaliano1)\
**Post date:** [August 15, 2020, 7:28pm UTC](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957/20 "2020-08-15T19:28:08Z")

</div>

> [@dpsanders](#):
>
> `using SymPy`

Ok I did this. See:

 ![image](https://global.discourse-cdn.com/julialang/original/3X/1/7/17e01b126bf1042002a082bd1330c255c12cd90b.png)  
But when I run using SymPy look:  
 ![image](https://global.discourse-cdn.com/julialang/original/3X/f/f/ff178d50ba0b2fc521f729ebe198e882f382680c.png)  
Julia say to run Pkg.build(“PyCall”) and never install…  
Please help me!!

[Next page](https://discourse.julialang.org/t/problems-in-use-symbolic-math/44957.md?page=2)