//: Playground - noun: a place where people can play

import Cocoa

var i = -6.28
while i < 6.28
{
    var s1 = 4*sin(i) / 3.14
    var s2 = 4*sin(3*i) / (3*3.14)
    var s3 = 4*sin(5*i) / (5*3.14)
    var s4 = 4*sin(7*i) / (7*3.14)
   
    s1
    s1+s2
    s1+s2+s3
    s1+s2+s3+s4
   
    i += 0.1;
}

你要表达什么？