# How to plot in 3D

**URL:** <https://community.freefem.org/t/how-to-plot-in-3d/3934>\
**Category:** General Discussion\
**Created:** [May 24, 2025, 1:03pm UTC](https://community.freefem.org/t/how-to-plot-in-3d/3934 "2025-05-24T13:03:46Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![weixj](https://avatars.discourse-cdn.com/v4/letter/w/4da419/32.png) [@weixj](https://community.freefem.org/u/weixj)\
**Post date:** [May 24, 2025, 1:03pm UTC](https://community.freefem.org/t/how-to-plot-in-3d/3934/1 "2025-05-24T13:03:46Z")

</div>

Now I want to solve the following system

 ![image](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/4/413eb4ce67f72e37d7f24a2e3c955022dba9eca0.png)

Suppose the computational region is `[0,1]^3` and the mesh `Th`. For the resulting numerical solutions, I would like to draw the magnetic field lines, velocity streamlines and vectors, and pressure contour plots at a given moment in the `y=0.5` section. How should I proceed?

```auto
real h = 1./10;
mesh3 Th = cube(1/h, 1/h, 1/h);

```

solutions:

```auto
ux, uy, uz; p; Bx, By, Bz.

```