HP 40gs hp 40gs_user's guide_English_E_HDPMSG40E07A.pdf - Page 117

hp40g+.book Page 13 Friday, December 9, 2005 1:03 AM To define your own fit Fit model Quadratic Cubic Logistic Exponent Trigonometric User Defined Meaning (Continued) Fits to a quadratic curve, y = ax2+bx+c. Needs at least three points. Fits to a cubic curve, y = ax3+bx2+cx+d. Needs at least four points. Fits to a logistic curve, y = 1-----+-----a--L-e---(------b--x---) , where L is the saturation value for growth. You can store a positive real value in L, or-if L=0-let L be computed automatically. Fits to an exponent curve, y = abx . Fits to a trigonometric curve, y = a ⋅ sin (bx + c) + d . Needs at least three points. Define your own expression (in Symbolic view.) 1. In Numeric view, make sure is set. 2. Display the Symbolic view. 3. Highlight the Fit expression (Fit1, etc.) for the desired data set. 4. Type in an expression and press . The independent variable must be X, and the expression must not contain any unknown variables. Example: 1.5 × cosx + 0.3 × sinx . This automatically changes the Fit type (S1FIT, etc.) in the Symbolic Setup view to User Defined. Statistics aplet 10-13