Question: fsolve outputs different solution when using complex parameter.

 

restart; P1vap := exp(16.6780-3640.20/(T-53.54)); P2vap := exp(16.2887-3816.44/(T-46.13)); gamma1 := exp(-ln(x1+A12*x2)+x2(A12/(x1+A12*x2)-A21/(A21*x1+x2))); gamma2 := exp(-ln(A21*x1+x2)-x1(A12/(x1+A12*x2)-A21/(A21*x1+x2))); A12 := V2*exp(-a12/(R*T))/V1; A21 := V1*exp(-a21/(R*T))/V2; a12 := 437.98*4.184; a21 := 1238*4.184; V1 := 76.92; V2 := 18.07; R := 8.314; EQ1 := P = x1*gamma1*P1vap+x2*gamma2*P2vap; EQ2 := x1*gamma1*P1vap = y1*P; EQ3 := x2*gamma2*P2vap = y2*P; P := 101.33; x1 := .85; x2 := .15

fsolve(EQ1, T, complex);

351.3118678

(1)

fsolve(EQ1, T);

-2.753166165

(2)

``

 

Download fsolve_problemEx.mw

I've recently run into a problem whereby I obtained different solutions from the fsolve command when the complex parameter was included. I had believed that by using the complex parameter, I would simply be shown the real solutions, as well as any complex solutions, though this does not seem to be the case. Would someone be able to explain what's occuring with the above code?

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