da_llxy_merc.inc

1 subroutine da_llxy_merc(lat, lon, proj, x, y)
2 
3    !-----------------------------------------------------------------------
4    ! Purpose: Compute x,y coordinate from lat lon for mercator projection
5    !-----------------------------------------------------------------------
6   
7    implicit none
8 
9    real, intent(in)              :: lat
10    real, intent(in)              :: lon
11    type(proj_info),intent(in)    :: proj
12    real,intent(out)              :: x
13    real,intent(out)              :: y
14    real                          :: deltalon
15 
16    if (trace_use_frequent) call da_trace_entry("da_llxy_merc")
17 
18    deltalon = lon - proj%lon1
19    if (deltalon < -180.0) deltalon = deltalon + 360.0
20    if (deltalon > 180.0) deltalon = deltalon - 360.0
21    x = 1.0 + (deltalon/(proj%dlon*deg_per_rad))
22    y = 1.0 + (ALOG(TAN(0.5*((lat + 90.0) * rad_per_deg)))) / &
23            proj%dlon - proj%rsw
24 
25    if (trace_use_frequent) call da_trace_exit("da_llxy_merc")
26 
27 end subroutine da_llxy_merc
28 
29