fsolve no solution found results

Hello,

I wanted to ask what does fsolve do after no solution has been found and it stops interating? Is the output the last iteration or does it output the initial conditions?

Also, is there a way when no solution has been found to tell it to output nothing, or for example an array of zeros?

Kind regards.

Answer 1

[Matt J]

Is the output the last iteration or does it output the initial conditions?

It is the last iteration, as you can easily test, .e.g.,

fsolve(  @(x) x^2+1,10  )

No solution found.

fsolve stopped because the problem appears regular as measured by the gradient,
but the vector of function values is not near zero as measured by the
value of the function tolerance.

ans = 5.5834e-09

Essentially, if no solution exists, fsolve can be thought of as a least squares solver.

Also, is there a way when no solution has been found to tell it to output nothing

No, but there is no reason why your code can't do its own post-assessment of the result after fsolve completes.

[Fernando]

Ok I see thank you!!

Answer 2

[Chunru]

doc fsolve for more details.

[x, fval, exitflag, output] = fsolve()    % check out exitflag and output