differentiation of vol for theta

Can you show me what is the answer?What is the answer?

dvol/dtheta?

clear();
r = 8;            % compression ratio
s = 100;          % stroke (mm)
b=s;              % bore=stoke
len= 150;         % connecting rod length (mm)
Vd= b^2*s*pi/4;   % displacement volume
Vc=Vd/(r-1);      % clearence volume
a=s/2;            % radius of crank shaft
theta=-180:1:180; % crankangle theta vector
y =len+a-((len^2-a^2*sind(theta).^2).^(1/2) +a*cosd(theta)); %  .^2).^  
vol= Vc+y*b^2*pi/4;  % exact volume

Answer 1

[Ameer Hamza]

Use gradient to differentiate vol with respect to theta numerically

dvol_dtheta = gradient(vol, theta);

[gultekin karahasan]

For example if i enter sinx it gives me cosx

what is this result of equation ?i want to only formulas like my example.

[Ameer Hamza]

To solve it symbolically, see this

syms theta

r = 8; % compression ratio
s = 100;   % stroke (mm)
b = s;         %bore=stoke
len = 150;

Vd = b^2*s*pi/4;     %displacement volume
Vc = Vd/(r-1);       %clearence volume
a = s/2;            % radius of crank shaft
y = len + a - ((len^2-a^2*sind(theta).^2).^(1/2) + a*cosd(theta));
vol = Vc + y*b^2*pi/4;  % exact volume
dvol_dtheta = diff(vol, theta);

[gultekin karahasan]

It does not work

[Ameer Hamza]

What is the error?

[gultekin karahasan]

Untitled1

[Ameer Hamza]

Paste this code in a script and press the run button. If there is error, paste the complete message.

[gultekin karahasan]

I do but it tells me only untitled.when u run this codes what is the answer? can u tell me ?i need only this answer.i have one answer but i did myself, i dont know its true or no?i have to check my result from matlab.

[Ameer Hamza]

Ah!!! It is not an error!!!! It shows that the code run successfully. Check the answer by typing this in command window

dvol_dtheta

[gultekin karahasan]

Sorry my friend,my experiences are so basic.i dont know how can i use matlab. i started use 2 days ago :(Thank u for helping u are amazing.

[Ameer Hamza]

No problem, you will learn with time. I am glad to be of help. You can try this course to get started in MATLAB: https://www.mathworks.com/learn/tutorials/matlab-onramp.html