Intersection of Two Polynomial Fit Curves

[ptc-4511010]

I'm a new user coming from using Excel for years. My company is looking into ways to streamline our design processes. I've downloaded the demo of Mathcad Prime 2.0 to see if it fit our needs. (On a side note, I think it is a shame that Prime 2.0 is missing seemingly major functionality found in Mathcad 15. Not being able to title or label plots is a big one for us.)

I thought I would start out my trial of Mathcad by using it in my current work on pump selection on a water delivery design I'm working on. So I have some pump data which I have plotted using a fit polynomial fit curve. On the same plot I have a polynomial curve fit to system data. In excel I can create this fit curve (called a trendline in excel) then have excel display the equation used to define the trendline. I can then use the equations of my two fit curves to find the intersection.

In mathcad I would think this would involve using a solve block, but since I used the regress() and interp() functions to make the fit curve, I'm not sure what syntax to use in the solve block. Any ideas?

[ptc-4511010 · Accepted solution]

I found it. I basically set up the interp functions like this:

G_system(x_s):=interp(x_system,y_system,z_system,x_s)

G_pump(x_p):=interp(x_pump,y_pump,z_pump,x_p)

Then the solve block was:

Guess Values:

x:=40

y:=70

Constraints:

G_pump(x)=y=G_system(x)

Solver:

find(x,y)=