The Software Science Language Level Metric

An important claimed result of Software Science is its ability to rank languages on the basis of the effort required to write a program. Halstead [1] defines the volume and program level of an implementation of an algorithm as (1) V=Nlog2 " (2) L = V'IV where nl = number of unique operators, nZ = number of unique operands, n ' " nl + nZ ' Nl =total occurrences of operators, NZ = total occurrences of operands, N ' " Nl + NZ ' and (3) V * ' " (n * + n*)log (n * + n*)1 2 212 is the potential or minimum volume. For a fixed algorithm V * is constant, and it follows from (2) that L and V are i.nversely related, Le. L decreases as the volume increases. The volume of a particular implementa-tion of an algorithm Il'ill, of course, change depending on the language being used. It may ~lso change because of individual programming style