Skip to main content
T
TR_97819639-Granite
9-Granite
May 25, 2022
Solved

No solution found for solveblock

  • May 25, 2022
  • 2 replies
  • 3864 views

I am getting error no solution found for solve block I tried to change the value for TOL and CTOL but with no luck

Best answer by LucMeekes

I can get minerr to work on (what I think is) your problem:

with:

LucMeekes_0-1654118404241.png

You can define a matrix M with:

LucMeekes_1-1654118448988.png

Which means that M is:

LucMeekes_2-1654118470031.png

The rank of M is still 9, instead of 10, and its determinant is still 0 (according to the symbolic solver), so there is not a single, unique solution; this is still the same problem you had before.

Now you want to solve a in M*a=C, using minerr (that is, find a solution that is close).

Your guess values for vector a can be constructed with:

LucMeekes_5-1654118688909.png

Your solve block might look like this:

LucMeekes_3-1654118540833.png

And see, it produces an answer. But how good is it?

M multiplied with R1 should produce C. Let's see:

LucMeekes_6-1654118831004.png

We can calculate the relative errors:

LucMeekes_7-1654118874967.png

C9 and C10 are pretty closely obtained, but C2 is 7.5 % off.

 

Success!
Luc

 

2 replies

L
LucMeekes23-Emerald IV
23-Emerald IV
May 25, 2022

You have 10 equations, and 10 unknowns, but that does not guarantee there is a solution.

Assuming this set is equivalent to yours:

LucMeekes_0-1653492162130.png

I get no symbolic solution, which may indicate that the equations may not all be independent from every other.

Are you sure this must lead to a solution?

 

Success!

Luc

 

W
Werner_E25-Diamond I
25-Diamond I
May 25, 2022

As Luc already suspected there is no solution for your system using the numbers you provided for the P, T and Q variables.

As you can see in the screen shot below, the rank of the coefficient matrix is less than  10 (which means there is no unique solution, either none at all or an infinite number of solutions). Because the rank of the extended c.matrix is 10 this means that the system has no solution.

Werner_E_0-1653507502921.png

Changing some input values can make you system solve. As an example if you change T5 from 600 to 601 the system has a solution.

 

rank(M)=9 should also mean that the determinant of the matrix is zero, but  Primes numeric thinks its as large as 10^27! That seems as a severe bug to me. The symbolic evaluation returns the correct result.

Werner_E_1-1653507614654.png

Because the numeric thinks that the determinant is not zero, it will also calculate an inverse of M and you could use this to calculate the solutions for the a-values.

Werner_E_2-1653507698874.png

 

But because the determinant actually is zero and the determinant therefore not invertible, you sure should not trust those results 🙂

 

You may also use "minerr" instead of "find" in your solve block to find a best approximation. Not sure if those values would be of any value for you, though.

Werner_E_3-1653507951000.png

 

 

 

    T
    TR_97819639-GraniteAuthor
    9-Granite
    May 26, 2022

    Thank you @Werner_E Werner for your inputs due to some conflicts I cannot share the files here in community.

    Terms & ConditionsCookie settingsAccessibility statement