[ddar]

Hello, I'm new in fortran and I would need a help

I'm working on a boundary element method code from the book "Boundary Element Programming in Mechanics" by Xiao-Wei Gao and Trevor G.Davies.

This code is capable of analyzing linear single-region problems of arbitrary geometry in both two or three dimensions and calulate displacement, traction, and stresses the body suppose to manage. I've attached the code.

I've also attached an input file data "CYLE2D".DAT" for a thick cylinder with internal diameter of 200 units and exernal diameter of 400 units, subjected to an internal pressure of 10 units under plane stress conditions. I would like to change the load conditions and apply an esternal load instead of the internal pressure and I would like to try a first case with a constand external load and a second case with a linear variable load.
How can I change this condition?

Thank you in advance!