Plotting the graph of change in Work wrt Crank Angle Degree

I am trying to plot the graph of Work with respect to Crank Angle Degrees. I have tried the code in following way.

% The pressure data 
pressure=xlsread('C:\Users\HP\Desktop\PROJECT WORK\Data.csv','M2:M1242'); 
Q=pressure*100;
% The Volume data
volume=xlsread('C:\Users\HP\Desktop\PROJECT WORK\Data1.csv','C2:C1242');
Z=volume*10^-9;
P0=101.325;
x=-160:0.25:150;
n=numel(x);
V= zeros(n,1);
w= zeros(n,1);
A= zeros(n,1);
for i= 1:numel(x)
    v=Z(i);
    V(i)=((0.249)*(10^-3))*sind(x(i)).*(1+((0.28*cosd(x(i)))./(sqrt(1-(0.0784*(sind(x(i)))^2)))));
    P=Q(i);
    w(i)=(P-P0).*V(i);
    A(i)=trapz(i, w);
end
plot(x,A','r')

X axis values are in Crank Angle Degrees

Y axis values are in Kilo Joules (kJ)

Kindly Suggest me the following things:

1.) If the code that I have written is correct.

2.) If the syntax for trapezoidal rule for Integration is right.

3.) How to check where the errors in getting the exact plot lies

[darova]

Please attach original equations

[Vishwajeet Ranjane]

Dear Sir/ Mam,

I need to plot the values for W at each value of x. The values of x vary from x(i=1)= -50 to x(i=100)= +50. W Vs x is the plot that I want to obtain. The equation is attached over here. Kindly help. The P values at each x are available.

Thanks and Regards

Answer 1

[darova]

What about limits? Here are limits for . But what about limits for ?

I think this line should be changed

 %A(i)=trapz(i, w);
 A(i) = trapz(x(1:i),w(1:i));

Read about cumtrapz