matlab simulink error help me

Hi I'm korean student

Error occurs I use the matlab in simlunk

I'm not actually sure why this error till you do not know how to fix

please teach me and help me matlab masters

code is

M size is 1 X 181
W and S is constant

this code is matlab function's parameter in simulink

-----------------------------------------------------------------------------

function [D,cd]= fcn(S, W, M)
%#codegen
for i=1:181;
    cl=W./(0.5*2116.2*1.4*S*M.^2);

    if M(1,:)<=0.8 ;
      cd0l=0.015;
      k=1/(pi*6*0.7);
    elseif M(1,:)>=1.2;
      cd0l=(0.015+(3*0.015-0.015)*(sin((2*pi)/3))^3);
      k=(1/(pi*6*(0.7-7*(0.4)^2+22*(0.4)^3)));
    else
      cd0l=(0.015+(3*0.015-0.015).*sin((M-0.8)./0.6*pi).^3);
      k=(1./(pi*6*(0.7-7*(M-0.8).^2+(M-0.8).^3).*22));
    end

cd=cd0l+k.*cl.^2*ones(1, 181);
D=0.5.*cd.*1.4.*2116.2.*S.*M.^2;

----------------------------------------------------------------------------

Where I want the value of the cd and D value. and Play the simulink and this error is

Size mismatch (size [:? x 1] ~= size [181 x 1]).
Mismatched varying and fixed sizes indicate a probable run-time error.  If this diagnostic is incorrect, use indexing to explicitly make the varying size fixed

Please tell me what the error is gone how

Answer 1

[Mitch Martelli]

Hi, You use a for statement but I cant see no one indexed variable inside the loop. Maybe you would like to to this :

num_col=size(M,2);
for i=1:num_col;
    cl(i)=W./(0.5*2116.2*1.4*S*M(i).^2);
    if M(i)<=0.8 ;
      cd0l(i)=0.015;
      k(i)=1/(pi*6*0.7);
    elseif M(i)>=1.2;
      cd0l(i)=(0.015+(3*0.015-0.015)*(sin((2*pi)/3))^3);
      k(i)=(1/(pi*6*(0.7-7*(0.4)^2+22*(0.4)^3)));
    else
      cd0l(i)=(0.015+(3*0.015-0.015).*sin((M(i)-0.8)./0.6*pi).^3);
      k(i)=(1./(pi*6*(0.7-7*(M(i)-0.8).^2+(M(i)-0.8).^3).*22));
    end
cd(i)=cd0l(i)+k(i).*cl(i).^2;
D(i)=0.5.*cd(i).*1.4.*2116.2.*S.*M(i).^2;
end

If yes, you can this program without use for statement in a easy form.

M1tCh

[Mitch Martelli]

Without for loop :

cl_trial=W./(0.5*2116.2*1.4*S*M.^2);
cd0l_trial=(0.015+(3*0.015-0.015).*sin((M-0.8)./0.6*pi).^3);
k_trial=(1./(pi*6*(0.7-7*(M-0.8).^2+(M-0.8).^3).*22));
case_a=find(M<=0.8);
cd0l_trial(case_a)=0.015;
k_trial(case_a)=1/(pi*6*0.7);
case_b=find(M>=1.2);
cd0l_trial(case_b)=(0.015+(3*0.015-0.015)*(sin((2*pi)/3))^3);
k_trial(case_b)=(1/(pi*6*(0.7-7*(0.4)^2+22*(0.4)^3)));
cd_trial=cd0l+k.*cl_trial.^2;
D_trial=0.5.*cd.*1.4.*2116.2.*S.*M.^2;

[Mitch Martelli]

M=rand(1,18100);

with for : Elapsed time is 4.856499 seconds.

without for : Elapsed time is 0.037057 seconds.

Answer 2

[Sutae]

Thanks, but I was having gave an error occurs

This error is Undefined function or variable 'cl'. The first assignment to a local variable determines its class.

and cl &k cd0l else

In my opinion, (i) think using those things tell me if there is another way

Note that I will try to run this program(simulink in matlab use matlab function)

[Walter Roberson]

Pre-allocate "c1" and "cd01" and "k" and "cd" and "d"

Also double-check your complete routine for the case where M is empty.