call 'routine_1.gp'  1 pi "title"
The three arguments are available inside routine_1.gp as follows
    ARG1 = "1"         ARGV[1] = 1.0
    ARG2 = "3.14159"   ARGV[2] = 3.14159265358979...
    ARG3 = "title"     ARGV[3] = "title"
In this example ARGV[1] and ARGV[2] have the full precision of a floating point
variable.  ARG2 lost precision in being stored as a string using format "%g".