Functionator 與 Least Squares Curve Fit 使用情況與統計

“Least Squares Curve Fit” is a user friendly, free of charge and free of ads app. User inputs point sets and chooses function types. Utilizing the Least Squares Linear Regression Method, the app calculates best fit curves, reports equations and draws graphs. Point sets can be stored in a table and are available after app is closed. Currently available function types are: 2D: 1. Line. 2. Parabola. 3. Polynomial up to 8th degree. 4. Circle. 5. Conic section (Ellipse or Hyperbola). 6. Trigonometric function as C + A1*cos(ω*x) + B1*sin(ω*x) + … + An*cos(n*ω*x) + Bn*sin(n*ω*x), where user can select n between 1 and 8 and enter any ω. 7. Exponential Function. 8. Bell Curve. 3D: 1. Plane. 2. Sphere. Also, there is an option to choose the Best Fit: the app goes through all the possible shapes and lists them in order from best to worst fit based on residuals. In some cases, when the standard Least Squares method with orthogonal projection does not work, best fit for Line, Parabola, Polynomial and Trigonometric functions can be calculated with SVD. Links to four other free apps by same developers are included in the app: 1. “Matrix Solver Step by Step” Linear Algebra Visual Guide. 2. “Polynomials and Linear Systems” Equation Solver. 3. “GraphMath” Graphing Calculator. 4. “Vectors and Planes” (and Spheres and Ellipsoids) 3D Geometry Guide. Developers hope to get feedback from users at graphmath@aol.com.