subroutine dmat(ym,pr,itdp,d)

C d= matrice [3×3], sigma= d*epsilon

    dimension d(3,3)
    if(itdp.EQ.0) goto 100
    if (itdp.eq.1) goto 200

100 continue

    ctp=ym/(1-pr**2)
    g=ym/((1+pr)*2)
    d(1,1)=1
    d(1,2)=pr
    d(2,1)=pr
    d(2,2)=1
    do 10,I10=1,2
    do 20,I20=1,2
    d (I10,I20)=d(I10,I20)*ctp

20 continue 10 continue

    d(1,3)=0
    d(2,3)=0
    d(3,1)=0
    d(3,2)=0
    d(3,3)=g
    return

200 continue

    cdp =ym*(1-pr)/((1+pr)*(1-2*pr))
    cpr=pr/(1-pr)
    g=ym/((1+pr)*2)
    d(1,1)=1
    d(1,2)=cpr
    d(2,1)=cpr
    d(2,2)=1
    do 30,I30=1,2
    do 40,I40=1,2
    d(I30,I40)=d(I30,I40)*cdp

40 continue 30 continue

    d(1,3)=0
    d(2,3)=0
    d(3,1)=0
    d(3,2)=0
    d(3,3)=g
    return
    end