Quote:
Originally Posted by julianh72
As Gary says:
e is the base of natural logarithms = approximately equal to 2.71828
https://en.wikipedia.org/wiki/E_(mathematical_constant)
Spreadsheet packages have an EXP() function, so you should code your expression as follows:
=4.96*EXP(-0.0118*REF)
where "REF" is the cell address of the x value.
Note: you might want to display the curve-fit expression with more significant figures - the 4.96 could be anywhere between 4.955 to 4.9649, and the 0.0118 could be any value between 0.01175 and 0.011849. You might need to carry more than 3 significant figures in your expression to get a good fit. (This may or may not matter with your particular data set.) |
Thanks Gary, just saw your reply.
Not sure why but what I ended up doing seems to be the same as your method up to 5 decimal places, after which they diverge slightly.
But as the math gurus concurr, I'll forge ahead using EXP in the form
=A*EXP(B*x)
Many Thanks, guys, I appreciate it.
Markus