# How to use Userdefined Symbolic function in Julia

**URL:** https://discourse.julialang.org/t/how-to-use-userdefined-symbolic-function-in-julia/26375
**Category:** General Usage
**Created:** [July 15, 2019, 7:26am UTC](https://discourse.julialang.org/t/how-to-use-userdefined-symbolic-function-in-julia/26375 "2019-07-15T07:26:14Z")
**Posts on this page:** 1
**Page:** 1

<div class="post-metadata">

### Author: ![Sivakumar](https://avatars.discourse-cdn.com/v4/letter/s/bb73d2/32.png) [@Sivakumar](https://discourse.julialang.org/u/Sivakumar)
#### Post date: [July 15, 2019, 7:26am UTC](https://discourse.julialang.org/t/how-to-use-userdefined-symbolic-function-in-julia/26375/1 "2019-07-15T07:26:14Z")

</div>

I am new to Julia. For my research problem, I have defined a function and try to call in Julia.  
function dens(x,l)  
return l_exp(-x_l)  
end  
using SymEngine  
x = symbols(:x)  
a = dens(x,5)  
a1 = mcall(float(m"integrate(dens(x,5),x,0,inf)"))  
I got the following answer.  
julia\> a  
5_exp(-5_x)

julia\> a1

```
                          inf
                         /
                         [
                         I dens(x, 5.0) dx
                         ]
                         /
                          0.0

```

But I need the integration value. Please help me to rectify this issue. Thanks in advance