Thread Subject: how to use optimisation tools in Matlab

i am trying to optimise the CL value of an aerofoil by varing a rotation angle theta

theta is fed into a function i will call 'F' to firstly rotate the co-ordinate points of an aerofoil

this aerofoil data is then fed into an external programme by 'F'

the data from the external programme is then called back into my function 'F'

this data is then plotted by 'F'

what i am having problems with is using an optimisation technique such as fgoalattain (x=fgoalattain(fun,x0,goal....) or fminimax to have the variable 'x' as theta, but the 'goal' to be finding the correct CL value from my function 'F'.

what i ultimately want to do is input a Cl value and the optimiser to vary theta until my Cl input value is met.

i have been pouring over this now for 2 weeks
and i am pulling my hair out.

Your function F should return the value of CL. Then you can use
fgoalattain.

Try this:
x0 = 0; % intial guess at theta, 0 may not be the best choice
weight = 1.0; %With only one goal, this should be set to 1.0.
CLGOAL = %put your goal value here

optimCL = fgoalattain(@F,x0,CLGOAL,weight);

Note you need to pass the function F in as a function handle (@F)
And your F function should be defined to return CL, and only accept x, or in
this case, theta as inputs.

function CL = F(theta)
% run simulation
% return CL

Stu



"Matthew " <men5mjr@leeds.ac.uk> wrote in message
news:gg1cbq$9gm$1@fred.mathworks.com...
>i am trying to optimise the CL value of an aerofoil by varing a rotation
>angle theta
>
> theta is fed into a function i will call 'F' to firstly rotate the
> co-ordinate points of an aerofoil
>
> this aerofoil data is then fed into an external programme by 'F'
>
> the data from the external programme is then called back into my function
> 'F'
>
> this data is then plotted by 'F'
>
> what i am having problems with is using an optimisation technique such as
> fgoalattain (x=fgoalattain(fun,x0,goal....) or fminimax to have the
> variable 'x' as theta, but the 'goal' to be finding the correct CL value
> from my function 'F'.
>
> what i ultimately want to do is input a Cl value and the optimiser to vary
> theta until my Cl input value is met.
>
> i have been pouring over this now for 2 weeks
> and i am pulling my hair out.