Naming Variables

Variables should have meaningful names, so that it’s easy for yourself and others to understand your analysis. Ravel uses the LaTeX text formatting language to enable users to create very informative variable names: English-language names can be augmented by superscripts and subscripts, and you can even use Greek letters (Chinese characters will be supported in a future release). A variable or parameter name can just be straight text (including spaces), but superscripts and subscripts, used wisely, can make the variables much easier to read:

To subscript a single character, precede it with an underscore “_” character;
To superscript it, precede it with a caret “^” character;
To subscript or superscript a string of text, enclose the text inside curly brackets (parentheses): {}; and
To write a Greek character, type the backslash key “\” followed by the English word for the Greek character.

Ravel Output	English entry	Ravel Input
BISHPIData	BISHPIData	BIS_{HPI}^{Data}
∆CreditHH%GDP	DCreditHH%GDP	\Delta{Credit}_{HH}^{%GDP}
Α α	Alpha	\Alpha,\alpha
Β β	Beta	\Beta,\beta
Γ γ	Gamma	\Gamma,\gamma
Δ δ	Delta	\Delta,\delta
Ε ε	Epsilon	\Epsilon,\epsilon
Ζ ζ	Zeta	\Zeta,\zeta
Η η	Eta	\Eta,\eta
Θ θ	Theta	\Theta,\theta
Ι ι	Iota	\Iota,\iota
Κ κ	Kappa	\Kappa,\kappa
Λ λ	Lambda	\Lambda,\lambda
Μ μ	Mu	\Mu,\mu
Ν ν	Nu	\Nu, u
Ξ ξ	Xi	\Xi,\xi
Ο ο	Omicron	\Omicron,\omicron
Π π	Pi	\Pi,\pi
Ρ ρ	Rho	\Rho,rho
Σ σ	Sigma	\Sigma,\sigma
Τ τ	Tau	\Tau,\tau
Υ υ	Upsilon	\Upsilon,\upsilon
Φ φ	Phi	\Phi,\phi
Χ χ	Chi	\Chi,\chi
Ψ ψ	Psi	\Psi,\psi
Ω ω	Omega	\Omega,\omega

Figure 28: Table of Greek characters supported by Ravel

When you combine characters, use the {} to differentiate, for example, Greek letters from English. For example, Figure 29 has the variable ∆ HPIReal, and that is created by typing {\Delta}HPI_{Real}.

You can enter variable names either by clicking on the Var widget and then choosing to enter a Variable or Parameter; or by simply typing anywhere on the wiring canvas. The latter action will bring up a text entry window, and when you press Enter (or click on OK) the variable and parameter definition window will pop up. Press Enter or click OK on that form—after adding additional details if desired, such as a Short or Long Description: the Short description functions as a “Tool Tip” which you’ll see when the mouse hovers over an entity, and it’s also used for Plot Legends—and the Variable or Parameter will be attached to the mouse cursor. Click where you want to place it on the canvas.