On Jun 26, 6:47 pm, nandan jha <[email protected]> wrote:
> Hello,
>
> I am using Mathematica to solve a set of equations and it keeps
> showing a error message "FindRoot::jsing: Encountered a singular
> Jacobian at the point {A1,A2,A3,Ea1,Ea2,Ea3} =
> {-2629.39,758889.,4.12521*10^6,-19229.4,-21903.5,-71770.6}. Try
I wonder if you might have an ill-posed problem. Even though there are
6 equations and unknowns, they always appear in a way that makes it
look like there are 9 unknowns:
Use the following definitions:
a=(8.314*(48 + 273.15))
b=(8.314*(44 + 273.15))
c=(8.314*(41 + 273.15))
sa=.0183
sb=0.00995
sc=0.0075
ca=0.01784
cb=0.00983
cc=0.00742
A1x=A1*exp(E1/x) where x is [a, b, c]
Then the equation set looks like this:
A1a + A2a + A3a == sa
A1b + A2b + A3b == sb
A1c + A2c + A3c == sc
A1a**2 + A2a**2 + A3a**2 + 2*A1a*A2a + 2*A3a*A2a - 2*A1a*A3a == ca**2
A1b**2 + A2b**2 + A3b**2 + 2*A1b*A2b + 2*A3b*A2b - 2*A1b*A3b == cb**2
A1c**2 + A2c**2 + A3c**2 + 2*A1c*A2c + 2*A3c*A2c - 2*A1c*A3c == cc**2
You can solve the 1st for A1a
A1a=>s1-A2a-A3a
...and substitute this into the 4th and solve for A2a
A2a=>(4*A3a*sa + ca**2 - sa**2 - 4*A3a**2)/(4*A3a)
...but there is no equation to resolve A3a.
Is there some other relationship between these quantities?
/c
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