deltat.frink

View or download deltat.frink in plain text format


// Program to plot Delta-T values

g = new graphics
p = new polyline

for y=1000 to 2500
{
   d = eval["#" + padLeft["$y", 4, "0"] + "#"]
   println["$d\t" + (deltaT[d]->s)]
   p.addPoint[JD[d], -deltaT[d]/s]
}

g.add[p]


p2 = new polyline
// Now read data from US Naval Observatory and overlay it.
for line = lines["http://maia.usno.navy.mil/ser7/deltat.data"]
{
   if [year, month, day, deltaT] = line =~ %r/\s*(\d{4})\s+(\d{1,2})\s+(\d{1,2})\s+(\d+\.\d+)/
   {
      month = padLeft[month, 2, "0"]
      day = padLeft[day, 2, "0"]
      date = parseDate["$year-$month-$day UTC"]
      println["$date\t$dt"]
      dt = eval[deltaT] s
      p2.addPoint[JD[date], -dt/s]
   }
}

g.color[0,0,1]
g.add[p2]
g.show[]


View or download deltat.frink in plain text format


This is a program written in the programming language Frink.
For more information, view the Frink Documentation or see More Sample Frink Programs.

Alan Eliasen was born 17590 days, 6 hours, 42 minutes ago.