MATLAB: How can I set axis’s tick or scale like photo.. help plz,,

axisplotrangescaletickxtick

CD = @(Re) 24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6);
fplot(CD, [0.1 1000000])

it is my result but I want like under. what should I use which command to get under.I know axis scale is a problem. I dont know which command need. please help me

Best Answer

Add these lines:

grid
set(gca, 'XScale','log', 'YScale','log', 'YLim',[0.01 100])

so the complete code is now:

CD = @(Re) 24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6);
fplot(CD, [0.1 1000000])
grid
set(gca, 'XScale','log', 'YScale','log', 'YLim',[0.01 100])

See Axis Properties for more options.

EDIT —

Added plot image —

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MATLAB: Calculation with using matrix is different from manual calculation

YOu have missed . in some places, check the below corrected line:

Re=10^5:10^5:10^6;
C_D = 24./Re + (2.6*(Re/5))./(1+(Re/5.0).^(1.52))+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/(10^6))./(1+Re/(10^6)) ;

MATLAB: ODE45 Code Application

Hi James,

[t,U] = ode45(@Velocity, [0, 20], .001);
plot(t,U)
function Udot = Velocity(t,U)
M = 100/6*pi*0.04^3;
g=9.8;
A=0.25*pi*0.04^2;
Re = 1.25*0.04*U/0.000015;
CD  = 24./Re+(2.6*Re/5)./(1+(Re/5).^1.52)+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/10^6)./(1+Re/10^6);
Udot = g -(0.5*1.25*U^2*A*CD)/M;
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You need to get ode45 outside of the functon definition. And you can calculate Re and CD without defining functions for them. If you do define Re and CD as functions, then calculating CD would require using Re(U) everwhere instead of just Re, and similarly CD would have to supplied with an argument. Easier here to not do that.

I changed the initial value of U to .001 since the 24/Re term blows up if you use zero. Changing the initial value does not seem to make much difference as long as it's small.

Best Answer

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