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 17836 days, 23 hours, 45 minutes ago.