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(C1) 'DIFF(F,X,2)=SIN(X)+'DIFF(G,X);
(C2) 'DIFF(F,X)+X^2-F=2*'DIFF(G,X,2);
is NOT the proper format. The correct way is:
(C3) 'DIFF(F(X),X,2)=SIN(X)+'DIFF(G(X),X);
(C4) 'DIFF(F(X),X)+X^2-F(X)=2*'DIFF(G(X),X,2);
The call is then DESOLVE([D3,D4],[F(X),G(X)]);
If initial conditions at 0 are known, they should be supplied before
calling DESOLVE by using ATVALUE.
(C11) 'DIFF(F(X),X)='DIFF(G(X),X)+SIN(X);
d d
(D11) -- F(X) = -- G(X) + SIN(X)
dX dX
(C12) 'DIFF(G(X),X,2)='DIFF(F(X),X)-COS(X);
2
d d
(D12) -- G(X) = -- F(X) - COS(X)
2 dX
dX
(C13) ATVALUE('DIFF(G(X),X),X=0,A);
(D13) A
(C14) ATVALUE(F(X),X=0,1);
(D14) 1
(C15) DESOLVE([D11,D12],[F(X),G(X)]);
X X
(D16) [F(X)=A %E - A+1, G(X) = COS(X) + A %E - A + G(0) - 1]
/* VERIFICATION */
(C17) [D11,D12],D16,DIFF;
X X X X
(D17) [A %E = A %E , A %E - COS(X) = A %E - COS(X)]
If DESOLVE cannot obtain a solution, it returns "FALSE".
(C3) IC1(D2,X=%PI,Y=0);
COS(X) + 1
(D3) Y = - ----------
3
X
(C4) 'DIFF(Y,X,2) + Y*'DIFF(Y,X)^3 = 0;
2
d Y dY 3
(D4) -- + Y (--) = 0
2 dX
dX
(C5) ODE2(%,Y,X);
3
Y - 6 %K1 Y - 6 X
(D7) ------------------ = %K2
3
(C8) RATSIMP(IC2(D7,X=0,Y=0,'DIFF(Y,X)=2));
3
2 Y - 3 Y + 6 X
(D9) - ---------------- = 0
3
(C10) BC2(D7,X=0,Y=1,X=1,Y=3);
3
Y - 10 Y - 6 X
(D11) --------------- = - 3
3
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