Logfit Formulator Function - Keithley 4200A-SCS Reference Manual

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Section 6: Clarius

LOGFIT Formulator function

Performs a base-10 log-linear fit.

LOGFIT(VX, VY, STARTPOS, ENDPOS)

Performs a base-10 log-linear fit as follows:

Fits the following logarithmic 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 = LOGFITA + LOGFITB * log(X)

where LOGFITA and LOGFITB are fit constants.

Using the above logarithmic 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.

GOODFIT = LOGFIT(GATEV, DRAINI, 30, 50)

(on page 6-255)

(on page 6-256)

The name of any column (vector) listed under Columns

For the range of X and Y values to be logarithmically fitted, the row number (index)

of the starting values

For the range of X and Y values to be logarithmically fitted, the row number (index)

of the ending values

Model 4200A-SCS Parameter Analyzer Reference Manual

4200A-901-01 Rev. C / February 2017