- Mathworld article on differential equations
- The Interactive Differential Equations site - includes lots of useful tools
- Companion site for the 4th edition - you can download the DE Tools software here
Plotting and solving
- slope fields: http://www.math.psu.edu/cao/DFD/Dir.html
- slope fields: http://www.ies.co.jp/math/java/calc/DiffEqu/DiffEqu.html
- phase plane plotter and solver for systems: http://scottsarra.org/applets/dirField2/dirField2.html
- 3D solver: http://techmath.uibk.ac.at/numbau/alex/dynamics/ode3d/
- Contour diagram grapher: http://www.flashandmath.com/mathlets/multicalc/contours/combo.html
Numerical methods
- Euler's method: http://www-math.mit.edu/daimp/EulerMethod.html
- Euler's method: http://www.calculusapplets.com/euler.html
- Comparing Euler, improved Euler, and Runge-Kutta: http://www.math.ubc.ca/~feldman/demos/demo2.html
Examples
- harvesting model applet: http://www.math.ksu.edu/math240/math240.f03/java/lab3/lab5.html
- damped harmonic oscillator: http://www.lon-capa.org/~mmp/applist/damped/d.htm
- Lorenz attractor: http://www.ii.uj.edu.pl/~mrozek/lorenz-applet/LORENZ.HTML
- Lorenz attractor: http://sprott.physics.wisc.edu/fractals/animated/lorenz.gif
- beats and resonance: http://web.mit.edu/jorloff/www/beats/beats.html
Linear algebra and complex numbers:
- Visualizing matrix multiplication, by David Austin, Grand Valley State
- Matrix calculator (including eigenvectors), by Robert Israel, UBC.
- Algebra and geometry of complex numbers: http://www.staff.science.uu.nl/~Ebeuke106/voorlichting/CompVis.htm
Maple