fsolve accuracy

Hi all,

I am fairly new to matlab so excuse my ignorance as this could be an easy problem.

I am using the fsolve function and it is working fine and it outputs my three parameters that I need. However all three numbers are limited to an accuracy of four decimal places which I would like to increase to 6 or even more.

Does anyone have any advice to help me improve the accuracy? This is a snapshot of the code...

Init_Guess = [0.05 0.02 0.0000406];

options=optimset('Display','iter','MaxIter',3000,'MaxFunEvals',3000, 'TolFun', 1.0e-12, 'TolX',1.0e-12);

Coeffs = fsolve(@Solution_1,Init_Guess,options)

As you can see with the Initial guess I am trying to force the code to increase the decimal places but it doesn't seem to want to do it.

Regards

John Mulvihill

Answer 1

[the cyclist]

My guess is that you are talking about what is displayed, as opposed to what is calculated. Try typing

>> format long

to see more digits in the output of the command window.

Answer 2

[Mahyar]

I have same problem too, and tried format long but it does not have any effect of the meaningful digits of results. Am I wrong?!

[John Mulvihill]

Hey Mahyar,

This answer from the cyclist solved it for me from what I remember! When I run the "fsolve" function in my code it calls on another .m file (Solution_1 from the example I gave) and within this file I have placed "format long" just after the "function" line which gives me 15 decimal places answers.

Example of Solution_1 file:

function Cost = Solution_1(Init_Guess)

format long

C1 = Init_Guess(1); C2 = Init_Guess(2); % these are the answers I want for whatever equation I put in

Cost = sum(C1 - C2) % this doesn't matter

end

The answer I get from this looks like the folllowing:

C1 = 0.008198986069043 and C2 = 0.005224578396002

Hope this helps

John