finding altitude using matlab atmosisa given pressure

hello, im trying to determine altitude using matlab atmosisa function, given P = 61.7*1000;

What is the best way to go about solving this, thank you.

matlab atmosisa function

[T,a,P,rho,nu,mu] = atmosisa(height)

% given 
p = 61.7*1000; % pascal

Answer 1

[Sam Chak]

Hi @Irfan

You can use this minimization approach.

altitude = ga(@costfun, 1, [], [], [], [], 3.9e3, 4e3)

ga stopped because the average change in the fitness value is less than options.FunctionTolerance.

altitude = 3.9926e+03

%% Check result
[~, ~, P, ~, ~, ~] = atmosisa(altitude)

P = 6.1700e+04

%% Cost function
function J = costfun(height)
    [~, ~, P, ~, ~, ~] = atmosisa(height);
    p   = 61.7*1000;
    J   = (P - p)^2;
end

Answer 2

[Walter Roberson]

You use the equation given in https://en.wikipedia.org/wiki/Pressure_altitude

Make sure you convert pascal to millibars .