# Programming the Dirac mass

**URL:** <https://community.freefem.org/t/programming-the-dirac-mass/215>\
**Category:** General Discussion\
**Created:** [January 10, 2020, 11:36am UTC](https://community.freefem.org/t/programming-the-dirac-mass/215 "2020-01-10T11:36:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![sellila](https://avatars.discourse-cdn.com/v4/letter/s/c67d28/32.png) [@sellila](https://community.freefem.org/u/sellila)\
**Post date:** [January 10, 2020, 11:36am UTC](https://community.freefem.org/t/programming-the-dirac-mass/215/1 "2020-01-10T11:36:23Z")

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Hello, i want programming this stationary equation but i don’t know, how i can programming the right hand side of this equation

-\mu \Delta C + (u.\nabla)C = \sum \limits\_{{i=1}}^N F\_i(t)\delta(r-r\_0)  
C(x,0) = C\_0  
delta is the dirac mass  
F\_i is the energy of the source.  
Someone can help me how i can programming the dirac mass with freefem???

Thank you.