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I am trying to solve a system of equations in Maple, but when I have it computing, I get a warning that says "solve may be ignoring assumptions on the input variables."

The Set-Up

My equations are polynomials in $x$ defined as letters $t$ through $z$ and coefficients as $a$ through $h$. I want to get expressions for the coefficients, which should be possible with 6 equations and 6 unknowns. These coefficients are defined as greater than zero since they correspond with forward moving rates. The set up is as follows:

t:= equation1, assume a>0,b>0,c>0,d>0, etc

u:= equation2, assume a>0,b>0...

...

z:= equation3,assume a>0,b>0...

solve({t,u,v,w,x,y,z},{a,b,c,d,e,f,g,h})

Alternative Set-Up

I have also tried putting the same list of assumptions within the solve command, but I get the same error. 

solve({equations},{variables},{assume a>0, etc})

The first few times I tried either of these, Maple would give me an answer that made $a=0$ and $b=0$, but now it won't even give me these trivial solutions, which is confusing. Any help would be greatly appreciated. Thanks in advance!

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    Maple's "assume" command doesn't work well. In particular, solve may not always know how to solve the system with the restrictions specified by the assumptions. – 2017-02-10
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    I recommend avoiding Maple's "assume" command entirely. Just apply the restrictions yourself _after_ solving. – 2017-02-10
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    I would, but it will give me solutions like a=0 and b=b which I can't go back through and correct without re-solving the system of equations. – 2017-02-10
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    If it's one particular system you are trying to solve, you could post it as a separate question, indicating that a symbolic computer solution is OK, preferably a Maple solution. – 2017-02-10

1 Answers 1

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You want to use solve(..., useassumptions = true) to ask solve to make sure it uses those assumptions.

Note that it is usually a better idea to put in the inequations directly into the system rather that as assumptions for the purposes of calling solve.

The help page solve/details (i.e. do ?solve,details in Maple) documents all the options that solve takes.