HP 39g hp 39g+ (39g & 40g)_mastering the hp 39g+_English_E_F2224-90010.pdf - Page 135

Choosing from available fit models On the hp 39g+ the Statistics aplet is the only one which has a SYMB SETUP view, and even then only in mode. This view is supplied to allow you to specify what type of fit equation is to be used. The choices are: Linear Logarithmic Exponential Power Quadratic Cubic Logistic and - m*X+b (Y = mX + b ) - m*LN(X)+b (Y = m ln ( X ) + b ) - b*EXP(m*X) (Y = b emX ) - b*X^m (Y = b X m ) - a*X^2+b*X+c (Y = aX 2 + bX + c ) - a*X^3+b*X^2+cX+d (Y = aX 3 + bX 2 + cX + d ) - L/(1+a*exp(-b*X)) this fits the data to a logistic curve (Y = 1 + L a e−bX ) where L is the saturation value. (see tip below) - User Defined - discussed below. Calculator Tip 1. If you want L calculated automatically, pre-store a value of zero into it. If the value is known, you can store a positive real value into memory L prior to the curve fit. 2. If you calculate a line of best fit and want to remove the resulting equation from the SYMB display and return to the 'm*X+b' display then just position the highlight on the relevant 'Fit:' line and press the DEL key. When you do this, the will be removed and will have to be reset. The User Defined model When you set the model to user defined it means that you are expected to supply the complete equation, including the values of any coefficients. The calculator will not calculate the values of any variables you include. For example, if you were to supply an equation of A /(X − B) as your model then the calculator would use the values of A and B currently in memory. 135