Reference: sum
sum(a1, a2, ..., an) returns the sum of the real or complex numbers a1, a2, ..., and an. sum(v) returns the sum of all components in the real or complex vector v.
sum(a1, a2, ..., an) returns the sum of the real or complex numbers a1, a2, ..., and an. sum(v) returns the sum of all components in the real or complex vector v.