D Values and Variables
GrafEq has three main groups of values and variables:
numbers, Roman letters, and Greek letters.
D.1 Numbers
Numbers 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.
Tip:  Infinity (∞) can be entered by pressing
Ctrl8 in GrafEq. 

D.2 Roman Letters
All 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 lowercase 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 Letters
All 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 lowercase 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 CtrlAlta.
Alpha  Α  CtrlAltA  α  CtrlAlta 
Beta  Β  CtrlAltB  β  CtrlAltb 
Chi  Χ  CtrlAltC  χ  CtrlAltc 
Delta  Δ  CtrlAltD  δ  CtrlAltd 
Epsilon  Ε  CtrlAltE  ε  CtrlAlte 
Phi  Φ  CtrlAltF  φ  CtrlAltf 
Gamma  Γ  CtrlAltG  γ  CtrlAltg 
Eta  Η  CtrlAltH  η  CtrlAlth 
Iota  Ι  CtrlAltI  ι  CtrlAlti 
Theta variant  ϑ  CtrlAltJ   
Phi variant    ϕ  CtrlAltj 
Kappa  Κ  CtrlAltK  κ  CtrlAltk 
Lambda  Λ  CtrlAltL  λ  CtrlAltl 
Mu  Μ  CtrlAltM  μ  CtrlAltm 
Nu  Ν  CtrlAltN  ν  CtrlAltn 
Omicron  Ο  CtrlAltO  ο  CtrlAlto 
Pi  Π  CtrlAltP  π  CtrlAltp 
Theta  Θ  CtrlAltQ  θ  CtrlAltq 
Rho  Ρ  CtrlAltR  ρ  CtrlAltr 
Sigma  Σ  CtrlAltS  σ  CtrlAlts 
Tau  Τ  CtrlAltT  τ  CtrlAltt 
Upsilon  Υ  CtrlAltU  υ  CtrlAltu 
Sigma variant  ς  CtrlAltV   
Pi variant    ϖ  CtrlAltv 
Omega  Ω  CtrlAltW  ω  CtrlAltw 
Xi  Ξ  CtrlAltX  ξ  CtrlAltx 
Psi  Ψ  CtrlAltY  ψ  CtrlAlty 
Zeta  Ζ  CtrlAltZ  ζ  CtrlAltz 

Figure D.1: Greek Alphabet and corresponding input key combinations
D.4 Sets
Sets 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.
Conclusion
To review:
 GrafEq relations can be specified in a wide latitude.
 Almost any letter is accepted as a variable name.
 In the Create View window any letter entered in a relation window
can be chosen as a domain or range variable; x, y, r, and θ
are always available as choices.
 For cartesian (rectangular) graphs, domain (horizontal axis) and
range (vertical axis) variables default to x and y; for polar graphs,
θ and r.
 In both cartesian and polar graphs, r defaults to the distance from the origin,
and θ to the position angle in radians.
 Each variable is a single letter; xy is the product of two variables and cannot be used as
a variable name.
 Some letters are reserved by GrafEq (namely, π, e, and ∞) and cannot be
used as variables.