              ! compute stability function             dCm  = d0  +  d0*an +  d0*as + d0*an*as + d0*an*an + d0*as*as             nCm  = n0  +  n0*an +  n0*as             nCmp = nt0 + nt0*an + nt0*as             call set(S_M,i, cm0_inv*nCm /dCm)             call set(S_H,i, cm0_inv*nCmp/dCm)         