MATLAB: I want to combine two anon functions, p(h) and t(p) and plot them against each other

anonymous functionsMATLAB

p= 29.921(1-6.8753*10^(-6)*h)^(5.2559)
T=49.161*log(p)+44.932

i want to write a script such that p and t are anon functs and then plot T against h with h from -500 to 14439

Best Answer

Hi,

the following code substitutes p in the equation for T with the expression from the first equation and creates a function handle:

syms h T
eq1 = 29.921*(1-6.8753e-6)*h^(5.2559)
eq2 = 49.161*log(p)+44.932
fun = matlabFunction(subs(eq2,p,eq1))

Then you can calculate values for T with given h and plot the result:

hval = linspace(-500,14439,1000);
Tval = fun(hval);
plot(hval,Tval)

Best regards

Stephan

Related Solutions

MATLAB: Calculating Air Density from altitude and then storing in a matrix

You need to modify your if else condition.....

Repalce:

   if h >36152

with

   if h >= 36152

actually when h=36152....value of rho is zero..so the problem. And also you have to initialize the values which you are filling in loop.

N = 65000 ;
rho = zeros(1,N) ;
for h =1:N
    if h >= 36152
        T=-70;
        p=473.1 * exp(1.73 - .000048*h);
        rho(h)=p/ (1718 * (T+459.7));
    elseif h < 36152
        T=59 - .00356*h;
        p=2116* ( (T+459.7)/518.6 )^5.256;
        rho(h)=p/ (1718 * (T+459.7));
    end
end
%

%
sigma= rho./0.00237717;
RC= 300;
x_10= 16.789;
eta_p= .68;
wp = zeros(1,N) ;
for i = 1:length(sigma)
    % density equation
    ws = linspace(1,4,length(sigma));
    wp(i) = eta_p./((RC./33000)+(ws(i)^0.5./(19.*x_10.*sigma(i)^.5)));
end
% Graph W/S and W/P
figure,
plot(ws,wp,'r-')
xlabel('W/S')
ylabel('W/P')

Note that above code can be vctorised. As you are a beginner, it is better to start with loops first and then vectorise.

MATLAB: Anonymous Function with natural log inside

Your functions are actually all functions of ‘h’. To refer to ‘p’ in ‘T’, you need to refer to it as ‘p(h)’.

This works:

p = @(h)29.921*(1 - 6.8753E-6.*h);
T = @(h)49.161*log(p(h)) + 44.932;
h = -500:14439;
p(h);
T(h);
plot(h,T(h))

Best Answer

Related Solutions

MATLAB: Calculating Air Density from altitude and then storing in a matrix

MATLAB: Anonymous Function with natural log inside

Related Question