<-[[.:start]] ====== DM41X Curve Fitting ====== Advantage Pac functions for statistical curve fitting. **CFIT** program provides the functions to fit statistics data to ''LIN'', ''Exp'', ''LOG'', ''Power'' and ''Best Fit'' XEQALPHA'C'FITALPHA * Save ''CFIT'' to a ''CST'' menu entry to make it easier to access * Clear Statistics Registers with 'C' (''CLΣ'') * Enter Statistics in usual way with ''Y'', 'ENTER', ''X'', 'A'(''Σ+'') * Don't use any data points ≤0 * When all data pairs are entered press 'E' (''FIT'') * Now choose which type of fit to use * ''L'' = Linear * ''LOG'' = Logarithmic * ''Ex'' = Exponential * ''P'' = Power * ''B'' = Best Fit * R/S to cycle through the coefficients of the curve fit ''a'', ''b'', ''R^2'' (error ratio) * You can next enter an ''x'' value to find the curve-fitted ''y'' value * pressing R/S can exit back to the Curves menu ''L LOG Ex P B'' to try a different fit to the same data * pressing R/S can exit back to the main menu to clear and enter a new set of data === Curve Fit values === * Linear ''y = a + bx'' * Ex ''y = ae^bx'' * Log ''y = a + b ln(x)'' * Power ''y = a x^b'' === Example of a Best Fit (LOG) === | X |0.72|1.31|1.95|2.58|3.14| | Y |2.16|1.61|1.16|0.85|0.5| * ''CFIT'' * ''CLΣ'' * ''2.16'' ENTER ''0.72'' 'A' (''Σ+'') * ''1.61'' ENTER ''1.31'' 'A' (''Σ+'') * ''1.16'' ENTER ''1.95'' 'A' (''Σ+'') * ''0.85'' ENTER ''2.58'' 'A' (''Σ+'') * ''0.5'' ENTER ''3.14'' 'A' (''Σ+'') * 'E' (''FIT'') * 'E' (''B'') //best fit// * display : ''LOG'' * R/S * display : ''a = 1.8515'' * R/S * display : ''b = -1.1021'' * R/S * display : ''r^2 = 0.9893'' * R/S * display : ''X=?'' * enter an X value if wanted, to get a ''y'' * ''1.5'' R/S * display : ''Y=1.4046'' * R/S * enter another, or press R/S again to exit to the curve fitting menu * try a different curve fit.... (''L'', ''Ex'' etc) or * R/S to exit to the top menu the curve found is '' y = 1.8515 - 1.1021 ln(x)'' --- //John Pumford-Green 31/07/24 14:46 BST// ===== Further Information ===== {{tag>calculator dm41x}}