Issue with Solve. Transition from Mathematica 9 to 10

Questions
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1

I just upgraded to Mathematica 10, but now I am having a bad time with a script which used to run perfectly in Mathematica 9. The issue comes in solving a system of equations with Solve function, one of the solutions contains a term highlighted in pink that shows a message when I pass the cursor over it: “No significant digits are available to display”. After applying FullSimplify to that solution, I get Indeterminate term instead of an equation.
Could it be that there is change in how Solve works in Mathematica 10? Is there any trick that might work?

2

When I copy that term in pink to the Notebook to see what it looks like, I get as an output
0``-9.295127339947216^(1 + 2.``6.005902655716767*A + B)

(A and B are symbols in my equation)

3

It appears that you are using floating-point numbers (d.dd) in your input to Solve. Try NSolve, which is designed to handle floating-point numbers.

Another method is to convert the equations to use only exact numbers.

In[1]:= equ = Rationalize[ 3.4 x^2 + x/2.2 == 0.137, 0]

Out[1]= 
   2
5 x   17 x     137
--- + ----- == ----
11      5      1000

In[2]:= Solve[ equ, x]

Out[2]=
        -250 - Sqrt[626118]         -250 + Sqrt[626118]
{{x -> -------------------},  {x -> -------------------}}
              3740                           3740

In[3]:= N[%]

Out[3]= {{x -> -0.278416}, {x -> 0.144726}}

My understanding is that 0``-9.295… means you have less than zero significant digits in the output. It may be that 9.0 simply did not check for such things.

4

I believe Bruce meant to say NSolve rather than NDSolve.

5

Thank you, David. I will fix my post.