Problem with a function

Hello everyone, I wrote this function:

function dz = nocontrol(v,z,parameters)

gammaT=??????????;
phi_0 =0.6;
psi_0 =0.6857;
psi_c0 = 0.3;
B=1.8;
Lc = 3; %m
W = 0.25;
H = 0.18;
C = 0;

dz = zeros(2,1);
dz(1)=(1/(4*B*B*Lc))*(z(2)-gammaT*(z(1))^0.5);
psi_c=psi_c0+H*(1+1.5*(z(2)/W-1)-0.5*(z(2)/W-1).^3);
dz(2) =(1/Lc)*(psi_c-z(1));
end

my problem is that I don't know how to write properly gammaT. I'd like to express it as a function, something like this:

gammaT_max = 0.8;
gammaT_min = 0.7;
A = (gammaT_max - gammaT_min)/2; %amplitude
b = gammaT_max - ((gammaT_max - gammaT_min)/2);
gammaT = A*sin(w*t)+b 

but I don't know how.

[madhan ravi]

what's your question? Are you asking if the way you defined the gamma function is correct?

[Paul Rogers]

I'd like to define gammaT as a function of the time, but I don't knwo how.

Answer 1

[Walter Roberson]

You have defined gammaT as a variable that you multiply by, but it needs to be a function of time. You will likely need something like

gammaT = @(t) A*sin(w*t)+b
dz(1)=(1/(4*B*B*Lc))*(z(2)-gammaT(SOMETHING)*(z(1))^0.5);

The SOMETHING would have to be replaced with your time variable, but it is not obvious that you have a time variable. Perhaps v is your time variable.

[Paul Rogers]

thank you, I'll give you alll the filles i am using to call this function.

1- run compressor2_data.m

2 - run general that calls the function nocontrol.m

when I wrote:

A*sin(w*t)+b 

i mean that t is time

[Walter Roberson]

You do not have a time variable, so I had to substitute the closest I could find.

function dz = nocontrol(v,z,parameters)

gammaT=parameters(1);
phi_0=parameters(2);
psi_0=parameters(3);
psi_c0=parameters(4);
B=parameters(5);
Lc=parameters(6);
W=parameters(7);
H=parameters(8);
C = 0;

gammaT_max = 0.8;
gammaT_min = 0.7;
A = (gammaT_max - gammaT_min)/2; %amplitude
b = gammaT_max - ((gammaT_max - gammaT_min)/2);
gammaT = @(t) A*sin(W*t)+b 

dz = zeros(2,1);
dz(1)=(1/(4*B*B*Lc))*(z(2)-gammaT(v)*(z(1))^0.5);
psi_c=psi_c0+H*(1+1.5*(z(2)/W-1)-0.5*(z(2)/W-1).^3);
dz(2) =(1/Lc)*(psi_c-z(1));
end

[Paul Rogers]

thanks a lot, you really solved me something I couldn't figured out.

just the argument in the sin was't W but another variable w in radians.

It woorks now