#!/usr/bin/perl
#
# (c) Vlad Kondratiev, 2007
#
if ($#ARGV == -1) {
 print "Usage: $0 <P in s> <Pdot in 10^(-15)>\n";
 print "The program gives a value of:\n";
 print " characteristic age, tau, in Myr\n";
 print " spin-down luminosity, Edot, in erg/s\n";
 print " surface magnetic field, Bs, in G\n";
 print " light-cylinder magnetic field, Blc, in G\n";
 print " Goldreich-Julian density, nGJ, in cm^-3\n";
 print " polar cap radius, Rp, in meters\n";
 print " light-cylinder radius, Rlc, in km\n";
 print " potential drop between the magnetic pole and the polar cap, dF, in V\n";
 print " rotational frequency, f, in Hz\n";
 print " derivative of rotational frequency, fdot, in sec^-2\n";
 exit 0
}
if ($#ARGV < 1) {
 print "you have set Pdot!\n";
 exit 1;
}
$pdot = $ARGV[1];
$p = $ARGV[0];
if ($pdot =~ /^-/) { $pdot =~ s/^-(.*)$/$1/; }

# age
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"15.8*($p)/($pdot)\" >> .ppdot");
 $tau = `bc -l < .ppdot`;
 chomp $tau;
 printf ("tau = %.3f Myr\n", $tau);
# Edot
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(3.95*10^31)*($pdot)/($p)/($p)/($p)\" >> .ppdot");
 $Edot = `bc -l < .ppdot`;
 chomp $Edot;
 printf ("Edot = %.3g erg/s\n", $Edot);
# Bs
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(10^12)*(sqrt($p*$pdot))\" >> .ppdot");
 $Bs = `bc -l < .ppdot`;
 chomp $Bs;
 printf ("Bs = %.3g G\n", $Bs);
# Blc
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(9.2)*(sqrt($pdot))/((sqrt($p))*($p*$p))\" >> .ppdot");
 $Blc = `bc -l < .ppdot`;
 chomp $Blc;
 printf ("Blc = %.3g G\n", $Blc);

 print ("\n");
# nGJ
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(7*10^10)*(sqrt($pdot/$p))\" >> .ppdot");
 $nGJ = `bc -l < .ppdot`;
 chomp $nGJ;
 printf ("nGJ = %.3g cm^-3\n", $nGJ);
# Rp
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(150)*(1./sqrt($p))\" >> .ppdot");
 $Rp = `bc -l < .ppdot`;
 chomp $Rp;
 printf ("Rp = %.3f m\n", $Rp);
# Rlc
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(4.77*10^4)*$p\" >> .ppdot");
 $Rlc = `bc -l < .ppdot`;
 chomp $Rlc;
 printf ("Rlc = %.3f km\n", $Rlc);
# dF
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"(2*10^13)*(sqrt($pdot/$p))/$p\" >> .ppdot");
 $dF = `bc -l < .ppdot`;
 chomp $dF;
 printf ("dF = %.3g V\n", $dF);

 print ("\n");
# f
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"1./$p\" >> .ppdot");
 $f = `bc -l < .ppdot`;
 chomp $f;
 printf ("f = %.15f Hz\n", $f);
# fdot
 system ("echo \"scale=30\" > .ppdot");
 system ("echo \"-1.*$pdot/($p*$p)\" >> .ppdot");
 $fdot = `bc -l < .ppdot`;
 chomp $fdot;
 printf ("fdot = %.15f sec^-2\n", $fdot);
 


system ("rm -f .ppdot");