Finding Axis Intercepts of Graph Intersection points.

[bhujanga]

Is there a way in excel to find the intersection of two line plots and create a line that goes from that point to the x and/or y-axis.

 

[SkipVought]

Hi,

Are you plotting two functions or two sets of points?

Skip,

_{Just traded in my OLD subtlety...
for a NUance!}

 

[bhujanga]

The plots are driven by sets of points. The values of the points have been derived from functions, but as far as the Excel sheet knows they are just sets of points.

 

[SkipVought]

Well, if the points are derived from functions, then could you not solve where function 1 equals function 2 for x & y?

Then you have two more line plots:
1) (0,y), (x,y)
2) (x,0), (x,y)


Skip,

_{Just traded in my OLD subtlety...
for a NUance!}

 

[bhujanga]

That could be done in this case, but we are trying to find a more general solution for when the function may not explicitly known but implied by a collection data. I am gathering, however, that Excel doesn't have a specific tool that does that. I was hoping it might be something they provided, similar to the trendline functionality that is built in that would plot the result automatically, thereby adjusting and replotting it whenever the data changed a little.

 

[SkipVought]

Please post your chart source data.

Skip,

_{Just traded in my OLD subtlety...
for a NUance!}

 

[mintjulep]

I'm attaching a spreadsheet with some VBA I made a long time ago "just because".

I never really fully developed it, or used it for anything.

It may serve as a starting point, or simply as amusement.

 

[combo]

Excel has SLOPE and INTERCEPT functions that give parameters for linear best fit function for (X, Y) datasets. Next you can solve system of two linear equations using excel functions: calculate determinat to test number of solutions (MDETERM),reverse matrix (MINVERSE, table array function), multiply matrix by matrix (MMULT, table array function).
The table array functions has to be entered by selecting proper output range (2x2 or 2x1 cells) and entered with CTRL+SHIFT keys (as standard array function).

combo

 

[bhujanga]

Thanks for your replies. I'm going to experiment with this last group of functions to see if anything within them will get there.