c
c
c =========================================================
subroutine src(maxmx,maxmy,meqn,mbc,ibx,iby,mx,my,q,
& aux,maux,t,dt,ibnd)
c =========================================================
c
c Copyright (C) 2003-2007 California Institute of Technology
c Ralf Deiterding, ralf@amroc.net
c
implicit double precision(a-h,o-z)
c
include "cuser.i"
c
dimension q(meqn, 1-ibx*mbc:maxmx+ibx*mbc,
& 1-iby*mbc:maxmy+iby*mbc)
dimension aux(maux, 1-ibx*mbc:maxmx+ibx*mbc,
& 1-iby*mbc:maxmy+iby*mbc)
dimension qstar(6)
c
c # 2-stage Runge-Kutta method:
c integrate source for gravity
c
dt2 = dt/2.d0
c
do 100 i=1-ibx*ibnd*mbc,mx+ibx*ibnd*mbc
do 100 j=1-iby*ibnd*mbc,my+iby*ibnd*mbc
c
qstar(1) = q(1,i,j)
qstar(3) = q(3,i,j) + dt2*grav*q(1,i,j)
qstar(4) = q(4,i,j) + dt2*grav*q(3,i,j)
c
c # second stage
c
q(3,i,j) = q(3,i,j) + dt*grav*qstar(1)
q(4,i,j) = q(4,i,j) + dt*grav*qstar(3)
c
100 continue
c
401 format(' RK integration failure in (',i5,',',
& i5,') t=',f20.12,' dt=',f20.12)
return
end
c