Each function also has an associated degree of either zero or one, depending on the result of the function. Multiplying two subexpressions yields a result whose degree is the sum of the degrees of the subexpressions. Dividing two subexpressions yields a result whose degree is the difference between the degrees of the subexpressions. Adding or subtracting two subexpressions yields a result whose degree is the same as the degrees of the subexpressions. Adding or subtracting two subexpressions that have different degrees is forbidden and causes an error exit.
Negation gives a result whose degree is equal to that of the subexpression.
The degree of the entire expression must be either zero or one. An expression with a degree of zero is considered to be a passband and an expression with a degree of one is a spectrum. Syncalc determines whether a file contains a passband or a spectrum by looking for a column of throughput values. The heart of syncalc is the set of functions that it supports.