CIGAL Reference Manual, Chapter 3 (Functions): measure
usage: result = measure(vlist,[scalefactor])
MEASURE calculates both the length and area defined by a list of graphics vectors, VLIST. If VLIST does not define a closed region the area value returned is 0. If SCALEFACTOR is specified, it is used to convert both output values from pixel units to other units. MEASURE always returns 2 output values: length first and then area.