c c c ========================================================= subroutine rp1ad1(maxmx,meqn,mwaves,mbc,mx,ql,qr,maux, & auxl,auxr,wave,s,amdq,apdq) c ========================================================= c c # solve Riemann problems for the 1D advection equation c # q_t + u(x) * q_x = 0. c c ----------------------------------------------------------- c # In advective form, with interface velocities specified in c # the auxiliary variable c # aux(i,1) = u-velocity at left edge of cell i c ----------------------------------------------------------- c c # On input, ql contains the state vector at the left edge of each cell c # qr contains the state vector at the right edge of each cell c # On output, wave contains the waves, c # s the speeds, c # amdq the left-going flux difference A^- \Delta q c # apdq the right-going flux difference A^+ \Delta q c c # Note that the i'th Riemann problem has left state qr(i-1,:) c # and right state ql(i,:) c # From the basic clawpack routine step1, rp is called with ql = qr = q. c c implicit double precision (a-h,o-z) dimension ql(1-mbc:maxmx+mbc, meqn) dimension qr(1-mbc:maxmx+mbc, meqn) dimension auxl(1-mbc:maxmx+mbc, maux) dimension auxr(1-mbc:maxmx+mbc, maux) dimension s(1-mbc:maxmx+mbc, mwaves) dimension wave(1-mbc:maxmx+mbc, meqn, mwaves) dimension amdq(1-mbc:maxmx+mbc, meqn) dimension apdq(1-mbc:maxmx+mbc, meqn) c c # Riemann solver returns flux differences c ------------ common /rpnflx/ mrpnflx mrpnflx = 0 c do 30 i=2-mbc,mx+mbc c c # Compute the wave and speed c u = auxl(i,1) c wave(i,1,1) = ql(i,1) - qr(i-1,1) s(i,1) = u amdq(i,1) = dmin1(u, 0.d0) * wave(i,1,1) apdq(i,1) = dmax1(u, 0.d0) * wave(i,1,1) 30 continue c return end