Quantum Wave in a Box vs GraphMath

Schrödinger equation solver 1D. User defined potential V(x). Diagonalization of hamiltonian matrix. Animation showing evolution in time of a gaussian wave-packet. In Quantum Mechanics the one-dimensional Schrödinger equation is a fundamental academic though exciting subject of study for both students and teachers of Physics. A solution of this differential equation represents the motion of a non-relativistic particle in a potential energy field V(x). But very few solutions can be derived with a paper and pencil. Have you ever dreamed of an App which would solve this equation (numerically) for each input of V(x) ? Give you readily energy levels and wave-functions and let you see as an animation how evolves in time a gaussian wave-packet in this particular interaction field ? Quantum Wave in a Box does it ! For a large range of values of the quantum system parameters. Actually the originally continuous x-spatial differential problem is discretized over a finite interval (the Box) while time remains a continuous variable. The time-independent Schrödinger equation H ψ(x) = E ψ(x), represented by a set of linear equations, is solved by using quick diagonalization routines. The solution ψ(x,t) of the time-dependent Schrödinger equation is then computed as ψ(x,t) = exp(-iHt) ψ₀(x) where ψ₀(x) is a gaussian wave-packet at initial time t = 0. You enter V(x) as RPN expression, set values of parameters and will get a solution in many cases within seconds ! - Atomic units used throughout (mass of electron = 1) - Quantum system defined by mass, interval [a, b] representing the Box and (real) potential energy V(x). - Spatially continuous problem discretized over [a, b] and time-independent Schrödinger equation represented by a system of N+1 linear equations using a 3, 5 or 7 point stencil; N being the number of x-steps. Maximum value of N depends on device’s RAM: up to 4000 when computing eigenvalues and eigenvectors, up to 8000 when computing eigenvalues only. - Diagonalization of hamiltonian matrix H gives eigenvalues and eigenfunctions. When computing eigenvalues only, lowest energy levels of bound states (if any) with up to 10-digit precision. - Listing of energy levels and visualisation of eigenwave-functions. - Animation shows gaussian wave-packet ψ(x,t) evolving with real-time evaluation of average velocity, kinetic energy and total energy. - Toggle between clockwise and counter-clockwise evolution of ψ(x,t). - Watch Real ψ, Imag ψ or probability density |ψ|². - Change initial gaussian parameters of the wave-packet (position, group velocity, standard deviation), enter any time value, then tap refresh button to observe changes in curves without new diagonalization. This is particularly useful to get a (usually more precise) solution for any time value t when animation is slower in cases of N being large. - Watch both solution ψ(x,t) and free wave-packet curves evolve together in time and separate when entering non-zero potential energy region. - Zoom in and out any part of the curves and watch how ψ(x,t) evolve locally.

This graphing calculator is user friendly and powerful.  It is fully compatible with iOS 14 and 15, and mostly compatible with iOS 13 and Mac OS. Cartesian 3D Z = F (X, Y) functions:  ——————————————————— Graphs can be:  1. Drawn as surface, lines, or dots. 2. Drawn with or without perspective, and with different light and reflection settings. 3. Tilted up or down. 4. Rotated to any position. 5. Drawing is animated by either X, Y, or Z. Table of all points can be sorted by either X or Y. Cylindrical 3D Z = F (Θ, R) functions:  ——————————————————— Graphs can be:  1. Drawn as surface, lines, or dots. 2. Drawn with or without perspective, and with different light and reflection settings. 3. Tilted up or down. 4. Rotated to any position. 5. Drawing is animated by Θ, R, or Z. Table of all points can be sorted by either Θ or R. Spherical 3D R = F (Θ, Φ) functions:  ——————————————————— Graphs can be:  1. Drawn as surface, lines, or dots. 2. Drawn with or without perspective, and with different light and reflection settings. 3. Tilted up or down. 4. Rotated to any position. 5. Drawing is animated by either Θ or Φ. Table of all points can be sorted by Θ, Φ, or R. Cartesian 2D Y = F (X) functions:  ———————————————— Graph displays the following curves: 1. One or two Y = F (X) functions. 2. Derivative of the first function. 3. Integral of the first function as a shade and a curve.  Graph features:  1. Drawing is animated by X. 2. Clicking on the curves shows curve values, and finds closest point in the table. Tables: 1.  All function, integral, and derivative values. 2.  Zero intersections of first function. 3.  Intersections between first and second functions. Polar 2D R = F (Θ) functions: ———————————————  Graph displays the following curves: 1. One or two R = F (Θ) functions. 2. Integral of the first function as a shade and a curve. Graph features:  1. Drawing is animated by Θ.  2. Clicking on the curves shows curve values, and finds closest point in the table. Tables: 1.  Table of all function and integral values  2.  Table of zero intersections of first function. 3.  Table of intersections between first and second functions. Parametric 2D X = F1 (T), Y = F2 (T) functions: —————————————————————————  Graph features:  1. Drawing is animated by T.  2. Clicking on the curves shows T, X, and Y values, and finds them in the table. Table of all points. F (X, Y) = 0  equations: ———————————— Graph displays solutions as points. Clicking on the points shows X, and Y values, and finds them in the table. Table of all points. Common features: —————————— 1. List of previous entries. 2. List of preset entries. 3. Undo and redo buttons for formula entries. 4. Automatic correction of errors in function limits or steps are offered. 5. All function points can be saved to clipboard in a table format. 6. All function points can be displayed on corresponding graphs. 7. Control colors can be changed to black and white. 8. Link to Vectors and Planes 3D Geometry Guide App. 9. Link to Matrix Calculator Step by Step App. Common features of all images:  1. Animation frames can be frozen and moved back or forward. 2. Animation speed can be adjusted. 3. Zoom. 4. Scroll. 5. Save to Clipboard. 6. Save to Photos 7. Color picker. New functions and further UI improvements for our apps are coming! Developers hope to get feedback at graphmath@aol.com.