Logfit - HP 48gII Advanced User's Reference Manual

Graphing calculator.

Input/Output:
ALOG, EXP, ISOL, LN

LOGFIT

Type:
Command
Description: Logarithmic Curve Fit Command: Stores LOGFIT as the fifth parameter in the reserved variable
PAR, indicating that subsequent executions of LR are to use the logarithmic curve-fitting
model.
LINFIT is the default specification in PAR.
Access:
...µ
LOGFIT
Input/Output: None
BESTFIT, EXPFIT, LINFIT, LR, PWRFIT
LQ
Type:
Command
Description: LQ Factorization of a Matrix Command: Returns the LQ factorization of an m × n matrix.
LQ factors an m × n matrix A into three matrices:
• L is a lower m × n trapezoidal matrix.
• Q is an n × n orthogonal matrix.
• P is a m × m permutation matrix.
Where P × A = L × Q.
Access:
Input/Output:
LSQ, QR
LR
Type:
Command
Description: Linear Regression Command: Uses the currently selected statistical model to calculate the linear
regression coefficients (intercept and slope) for the selected dependent and independent
variables in the current statistics matrix (reserved variable DAT).
The columns of independent and dependent data are specified by the first two elements in the
reserved variable PAR, set by XCOL and YCOL, respectively. (The default independent and
dependent columns are 1 and 2.) The selected statistical model is the fifth element in PAR. LR
stores the intercept and slope (untagged) as the third and fourth elements, respectively, in PAR.
The coefficients of the exponential (EXPFIT), logarithmic (LOGFIT), and power (PWRFIT)
models are calculated using transformations that allow the data to be fitted by standard linear
regression. The equations for these transformations appear in the table below, where b is the
intercept and m is the slope. The logarithmic model requires positive x-values (XCOL), the
exponential model requires positive y-values (YCOL), and the power model requires positive x-
and y-values.
3-98 Full Command and Function Reference
Level 1/Argument 1
z
'symb'
FACTORIZATION LQ
MATRIX FACTORS LQ
Level 1/Argument 1
[[ matrix ]]
A
( Ø is the left-shift of the 5key).
( ´ is the left-shift of the Pkey).
Level 3/Item 1
Level 2/Item 2
[[ matrix ]]
[[ matrix ]]
L
Level 1/Item 1
log z
'LOG(symb)'
Level 1/Item 3
[[ matrix ]]
Q
P  