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D Values and VariablesGrafEq has three main groups of values and variables: numbers, Roman letters, and Greek letters.D.1 NumbersNumbers are formed from the ten numeric digits (0 to 9), the decimal point, and the negation sign. Numbers are always numeric constants. Digits cannot be used as variables.Numbers can be entered via the computer keyboard, the numeric key pad, or by using the easy button floating window.
D.2 Roman LettersAll Roman letters except e can be used as variables or constants. GrafEq predefines e as 2.7182818284590452..., the base of natural logarithms. GrafEq is case sensitive, so upper- and lower-case letters are considered different and unique; x and X are not the same.Roman letters can be entered via the computer keyboard or by using the easy button floating window. D.3 Greek LettersAll Greek letters except π can be used as variables or constants. The Greek letter π is a predefined constant in GrafEq, equal to 3.1415926535897932..., and is a half circle’s angle in radian measure. GrafEq is case sensitive, so upper- and lower-case letters are not the same; ω and Ω are two different variables.Greek characters can be entered via the easy button floating window, by typing in their name, or by using the keyboard key combinations listed in figure D.1. For example, “α” may be entered by clicking on the appropriate easy button, by typing “alpha”, or by pressing Ctrl-Alt-a.
Figure D.1: Greek Alphabet and corresponding input key combinations D.4 SetsSets can be discrete or continuous. A discrete set contains elements listed within a pair of braces: for example, {2,5} or {x,sinx}. A continuous set can either contain open ranges described within a pair of parentheses, or closed ranges described within a pair of square brackets: for example, (0,1) or [-1,4]. Combinations, such as {1,[2,x]} and {(1,4],cosy}, are certainly possible.ConclusionTo review:
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