Keithley 4200A-SCS - Line Fits; EXPFIT Formulator Function

Model 4200A
-SCS Parameter Analyzer Reference Manual Section 6:
Clarius
4200A-901-01 Rev. C / February 2017 6-247
Line Fits
The Line Fit Formulator functions allow you to set up different types of line fits.
EXPFIT Formulator function
Performs an exponential fit. Fits the following exponential relationship to a specified range of values in two
columns (vectors): one column, VX, containing X values and the other column, VY, containing Y values:
Y = EXPFITA * e
(EXPFITB * X)
Where EXPFITA and EXPFITB are fit constants.
Usage
EXPFIT(VX, VY, STARTPOS, ENDPOS)
VX
The name of any column (vector) listed under Columns
VY
The name of any column (vector) listed under Columns
STARTPOS
For the range of X and Y values to be exponentially fitted, the row number (index) of
the starting values
ENDPOS
For the range of X and Y values to be exponentially fitted, the row number (index) of
the ending values
Details
Using the above exponential relationship, returns a new column (vector) containing Y values
calculated from all X values in column VX.
If a VX or VY value at either STARTPOS or ENDPOS is an invalid number (that is, the value is #REF),
the function will not return a valid result.
Example
DIODEI = EXPFIT(ANODEV, ANODEI, 2, LASTPOS(ANODEV))
Also see
EXPFITA (on page 6-248)
EXPFITB (on page 6-249)