Instructions for use of mathematics in Environment and Planning journals
Multiletter variables should not be used, because mathematically they cannot be distinguished from the product of two single-letter variables—for example, CL = C × L. Instead, subscripts or superscripts should be used to differentiate between similar variables or variables of the same family (C = CL+CT+CM).
Care should be taken to format variables in italic (x); operators, descriptors, and constants upright (d); vectors in bold italic (v); and matrices in bold upright (M). Computer variables (or any programming syntax) should be clearly labelled as such, as they will be set in a sans-serif font.
All variables should be defined in the text on their first use and should be denoted in the same way throughout the paper [eg P(i) should not later be referred to as P]; the same letter should not be used to denote more than one variable (unless subscripts or superscripts are used to differentiate, as shown above).
Care should be taken to avoid any ambiguity in mathematics:
lnxy = ylnx or ln(xy)? x + 2z / y = x + (2z / y) or (x + 2z) / y?
Mathematics should be set with a diagonal division bar when used in the text [for example: (x2 + 3x) / (1 + y)], and with a horizontal division bar when set out of text as an equation:
