bjdaz2 (zlat0,alon0,zlat,alon,delt,az1,az2,lattype) elpcr (elat,delta,azdg,depth,elpc,iphase,ic) find (x,xt,n,ians) readiasp (lun) getiasp (del,dep,pt,st,dpdx,dpddep,dsdx,dsddep) glat (hlat) redtab (lun)
subroutine bjdaz2 (zlat0,alon0,zlat,alon,delt,az1,az2,lattype) real*4 zlat0,alon0,zlat,alon,delt,az1,az2 integer lattype calculate geocentric distance, azimuth, and back azimuth from a c reference point to another point on the earth's surface. c input arguments: c if lattype = 1 then c zlat0 = geocentric latitude of reference point. c zlat = geocentric latitude of point c if lattype = 0 then c zlat0 = geocentric colatitude of reference point. c zlat = geocentric colatitude of point c c alon0 = longitude of reference point. c alon = longitude of point c c output arguments: c delt = epicentral distance c az1 = azimuth of the point from the reference point. c az2 = azimuth of the reference point from the point. c c *** note *** c all angles are in radians. c north latitude and east longitude are positive. c azimuth is measured clockwise from north. c if one point is at north or south pole, azimuth from that c point will be the limit of the azimuth as the pole is c approached along the meridian whose longitude is given.
subroutine elpcr (elat,delta,azdg,depth,elpc,iphase,ic) real*4 elat,delta,azdg,depth,elpc integer iphase,ic
c Compute ellipticity correction from dziewonski and gilbert c Geophys. J. R. Astr. Soc. (1976) 44, 7-17. c elat = epicentral latitude c delta = distance in degrees c azdg = azimuth from epicenter to receiver in degrees c depth = earthquake depth in km. c iphase = 0 for p or 1 for s c elpc = ellipticity correction in seconds c if input latitude is in geographic (?geocentric?) degrees ic=0 c if input latitude is in geocentric radians ic=1
find (x,xt,n,ians)
real*4 x(n), xt integer n, ians Sorting utility used by REDTAB c x is a monotonically increasing vector of dimension n. c xt is greater than or equal to x(ians) but less than c x(ians+1).
readiasp (lun) reads iaspei travel-time curves from disk: /etna/home/abers/IASPEI/iaspei.time2 -- Call before getiasp()
getiasp (del,dep,pt,st,dpdx,dpddep,dsdx,dsddep) real*4 del,dep,pt,st,dpdx,dpddep,dsdx,dsddep
c interpolates iaspei table to get times at del,dep and derivatives c also, numerically calculate derivatives w/distance c d.dx is in sec/deg, d.dz id in sec/km; del in deg, dep in km
glat (hlat) real*4 hlat
c------convert geographic latitude to geocentric latitude------------- c hlat (input) = geographic latitude in radians (north positive) c glat (output)= geocentric latitude in radians (north positive) c---------------------------------------------------------------------
redtab (lun)
c read file of ellipticity corrections: call before elpcr()