## Multivariable Calculus Apps:

## Differential Equations Apps:

**Direction Field Explorer** (opens in a new window) – an app designed to allow you to visually verify the general solution of a 1st-order differential equation. You can enter the differential equation, solved for dy/dx (or whatever variables it involves, setting these in the app). You can also enter the general solution using the independent variable and *C* as the parameter. This parameter *C* can then be varied either with the scrollbar or by entering a value to see if the resulting solution curve fits nicely in the direction field or not. If the vectors/slope segments are not tangent to the path of the curve at all points, the general solution is not correct. That is, if for some value of *C*, the solution curve does not go with the flow of the vectors in the direction field, then the general solution is incorrect.

## Linear Algebra Apps:

**LinAlg4x4** (opens in a new window) – a simplified version of CalcPlot3D that allows the user to apply a 4 x 4 transformation matrix to a 3D surface and the containing box to see its effect. The matrix can then be varied or left unchanged and applied to the view ,multiple times.