$MachineID (Built-in Mathematica Symbol)

$MachineID is a string that gives, if possible, a unique identification code for the computer on which Mathematica is being run.

$Notebooks (Built-in Mathematica Symbol)

$Notebooks is True if Mathematica is being used with a notebook-based front end.

$OperatingSystem (Built-in Mathematica Symbol)

$OperatingSystem is a string giving the type of operating system under which Mathematica is being run.

$System (Built-in Mathematica Symbol)

$System is a string describing the type of computer system on which Mathematica is being run.

$UserDocumentsDirectory (Built-in Mathematica Symbol)

$UserDocumentsDirectory gives your default "documents" directory.

Algebraic Manipulation (Mathematica Overview)

Structural Operations on Polynomials Finding the Structure of a Polynomial Polynomial Orderings

Constrained Optimization in ... (Mathematica Tutorial)

[1] Mehrotra, S. "On the Implementation of a Primal-Dual Interior Point Method." SIAM Journal on Optimization 2 (1992): 575–601. [2] Nelder, J.A. and R. Mead. "A Simplex ...

Editing Mathematica Graphics Overview (Mathematica Overview)

Introduction to Editing Mathematica Graphics Drawing Tools Selecting Graphics Objects

Exact and Approximate Results (Mathematica Tutorial)

A standard electronic calculator does all your calculations to a particular accuracy, say ten decimal digits. With Mathematica, however, you can often get exact results. ...

Getting Pieces of Lists (Mathematica Tutorial)

Picking out elements of lists. We will use this list for the examples. Here is the last element of t.