graph drawing software

GeX · 12 Dec 2007 at 21:40

hi.. wasnt really sure where to put this or what to search for.. hopefully someone will have some clue what im waffling on about

basically, i have a table of data which is 14x14, and i need to put that data in my table which is 12x12.

the data is ignition advance values for my car, with RPM along the bottom and MAP up the side.

The max and min values on each scale need to remain, but i need to recalculate all the points in between.

Current scale goes up in 400rpm chunks, new one in 550rpm chunks

What i was thinking of doing was plotting a column of data at a time, individiually and then using the graph to calculate what value i should have 550rpm, 1100rpm etc

I tried using excel for this, but it won't tell me intermediate values.

Anyone know any software that would, or im going to end up printing the graphs and getting my ruler out!!

Rich_L · 12 Dec 2007 at 22:01

If you do an Excel graph, there an option to display the equation of a trendline.

Put the equation back into Excel and that should work

There might be a more elegant solution out there but this should work!

i.e. if the trendline equation displays y = x^2 + 3x - 4

Then put in a cell -> =(A1^2)+(3*A1)-4

Where A1 is your point you want a y value for

GeX · 12 Dec 2007 at 22:16

i dont think that'd work, there is no trend on the graph, the gradient varies, and it isn't constantly increasing decreasing.

Coran · 12 Dec 2007 at 22:18

There must be some pattern to it? Maybe post a pic of the results and someone might suggest another method.

I was actually trying to find a way of doing this myself this week. Some graphs excel is simply not capable of finding an equation for.

GeX · 12 Dec 2007 at 22:23

hmm!

Rich_L · 12 Dec 2007 at 22:36

From the first line it looks like a cubic polynomial, i.e. x^3, dunno about the other ones though, might take a look later if I have a bit of time

GeX · 12 Dec 2007 at 23:21

i dont think its an anything, there is no relationship between the two scales - it is a settings file, an ignition map for my ECU..

i was only look at making a graph out of the colums so i can calcuate the intermediate values between the RPM points that are shown.