The following are links to some useful interactive symbolic and numerical math calculators located on the

WWW
Interactive Mathematics Server

&

Numerical Methods:
Root finding, integration, differential equations

Calculator:
General purpose calculator (complex numbers and more) (screen
shot)

Calculus:
Computes derivatives, integrals, limits, Taylor, root solver … (screen shot)

Linear
Systems: Computes solution to a set of linear equations,
… (screen shot)

Matrix:
Computes inverse, determinant, eigenvectors, … (screen shot)

Series
Sum: Computes sums of infinite series or other finite sums,
… (screen shot)

Polynomial
Roots: (by Wolfram) (screen shot)

Differential
Equation Solution: (by Wolfram) (screen shot)

Partial
Fraction Expansion: (by Wolfram) (screen shot)

Laplace/Fourier
Transorms
(screen shot)

Function
Plotter: Plots 2D and 3D functions with zooms, deforms, and rotates, … (animated plot)

Parametric
plot: Plots parametric curves (state-space trajectories) with moving points, … (animated plot)

Animated
Sequence: Visualize a sequence of real functions (e.g., Fourier expansion), … (animated plot)