A pair of months ago I downloaded a package that can be used in mathematica. It is a special package for high energy physics and one of the commands can be used to solve a group of diferential equations that are important for the topic. I can use this comand and save the result in a new variable in order to plot this but the real problem appear when I want to know the real value of the function evalueted in a particular point of its independent variable. To solve these equations I didn't have to use the command DSolve or NDSolve but instead I use a special command of the package, however I think it is similar to a NDSolve. When I try to get the numeric value of the solution I get a large thing with something with the name of InterpolationFunction, I saw the wolfram manual and I cannot still get the numeric result. How can I work with this in order to get the numeric value?
I would use it in the ways shown in the documentation pages for InterpolatingFunction and NDSolve. (Probably the package uses NDSolve to produce it.)
Perhaps, as you seem to imply, the way you followed the documentation did not work. In that case, I think you need to share exactly what you tried (along with the exact form of the solution returned by the package).