ODE45 How to use atmosisa function with Height function as Input?

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Hafizuddin Bin Mohd Lowhim
编辑： Hafizuddin Bin Mohd Lowhim 2020-5-27
Hello,
I need help to configure how to use atmosisa function if we need to use height function h(t) as input? In this ODE45, I set variable z to be z(1), z(2), z(3) and z(4). z(2) is the height variable. When I put height to be 1000m, the code does work but when I put in as z(2) as input, it gives error.
Density.m
function rho=density()
[~, ~, ~, rho]=atmosisa(z(2));
end
rhs_trajectory
function dz = rhs_trajectory(z,g,F,F_d,m,gamma)
x = z(1);
y = z(2);
v_x = z(3);
v_y = z(4);
dx = v_x;
dy = v_y;
dv_x = ((F-F_d)/m)*cos(gamma)-m*sin(gamma);
dv_y = ((F-F_d)/m)*sin(gamma)-g;
dz = [dx; dy; dv_x; dv_y];
end
I attached other necessery function for reference. Please help me.
  1 个评论
darova
darova 2020-5-27
The question is unclear
  • You are passing some argument into atmosisa, but not passing into density
function rho=density() % z(2) should an argument
[~, ~, ~, rho]=atmosisa(z(2));
end
  • i don't see you use density function. Where do you want to use it?

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回答（1 个）

Star Strider
Star Strider 2020-5-27
‘but when I put in as z(2) as input, it gives error’
That is most likely because you do not pass it as an argument to your ‘density’ function.
Try this:
function rho=density(x)
[~, ~, ~, rho]=atmosisa(x);
end
(I also do not see where you called it in your ‘rhs_trajectory’ function.)
I do not have the Aerospace Toolbox, so I cannot test this directly. However the problem appears to be obvious.

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