Thank you for your prompt reply.
I'm solving the 2D Helmholtz problem on a Cartesian plane. u''(x,y)+q*u(x,y)=f(x,y)
Above governing equation, f(x,y) is external or internal source and Dirac Delta Function.
I want to compare analytical solution with numerical solution.
I have analytical solution.
To obtain numerical solution, Dirac Delta Funtion code is needed.
I know the function can not be expressed directly.
So, in detail, my question is how is the approximated expression of Dirac Delta Function.
Thank you in advance
Singularities make for beautiful mathematical solutions. They are physically incorrect and numerically intractable. It is quite unreasonable to expect a general purpose language such as Fortran to have special features to treat singularities.