Integral Function Issue

[kcotton]

Hello,

I'm trying to use the integral function of MathCAD, which I haven't used before, and getting  "This calculation doesn't converge to a solution".  I think it has something to do with using a ray with the specific values for integration. I included the graph of what I'm trying to integrate. Any help would be great.

Thanks,

Kendall

[RichardJ]

If you want to use the integrals in Mathcad you have to integrate a function. The best way to turn your data into a function is usually spline interpolation, but for your data rational function interpolation may well be better. To integrate data directly you would have to use the trapezoidal rule or Simpson's rule. See "Help", "Data analysis extension pack", "Application examples", "Numerical integration of data" for details of either approach.

[-MFra-]

My attempt to resolve the issue. See the attached worksheet.

[Fred_Kohlhepp]

You have "solved" the problem by (luckily) finding symbolic functions for each of your integrals, congratulations.

So Mathcad was able to evaluate the integral at each point there was data.

But your first heuristic solution integral is the integral of a constant between two points:

Now, if that's what you want great, but if you want to integrate that curved function, this isn't it.

[-MFra-]

... It is clear what you say. And what about the second heuristic solution?

[Fred_Kohlhepp]

Attached is a mod to you file showing what Richard suggested--develop a function that fits your data.  When I try to extend that to the integral there is an issue with your limits of integration.

Here's your start.  Good luck.

[Fred_Kohlhepp]

Getting closer!