# Explicit and implicit Euler Schems

**URL:** https://community.freefem.org/t/explicit-and-implicit-euler-schems/695
**Category:** General Discussion
**Created:** [December 18, 2020, 8:18pm UTC](https://community.freefem.org/t/explicit-and-implicit-euler-schems/695 "2020-12-18T20:18:17Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Aicha](https://avatars.discourse-cdn.com/v4/letter/a/ec9cab/32.png) [@Aicha](https://community.freefem.org/u/Aicha)
#### Post date: [December 18, 2020, 8:18pm UTC](https://community.freefem.org/t/explicit-and-implicit-euler-schems/695/1 "2020-12-18T20:18:17Z")

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Hi,  
i have the following system:

 ![Capture](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/1X/6891fe0f4c9cc6e66b97a5eabc89df72b1a310a9.png)

An explicit Euler scheme of the equations (0.1) and (0.2) give:

real t=0.0;

real dt=0.1;

real tau=1;

real n= tau/dt;

Vh U, I, Udecale, Idecale;

(Udecale -U)/dt = -k2_U_V

(Idecale-I)/I=k2_U_V-sigma1\*I

An Euler implicit scheme of the equation (0.3) is:

Vh V, Vold

(V-Vold)/dt=D_d^2V/dx^2+k\_3_I(x,t-n_dt)-sigma2_V

My question is: How we can obtain three linear equations after using this schems? Is it possible?

Thank’s in advance.