How to Calculate Area Between a Curve and Two Lines?

2 views (last 30 days)
shahin sharafi on 15 Aug 2021
Commented: shahin sharafi on 16 Aug 2021
Hi Everyone,
I am trying to calculate area (yellow area in attached figure) between curve and vertical and horizental axies lines. the code is provided as below. Could anyone help me?
Thank you in advance for you help.
Thank you,
clear all
clc
close all
%%
m=60;L=1;J=60;g=9.81;beta2=411.67;
KPb=2.15;KDb=0.75;
Time_Delay_Brain=0.19;
Time_Delay_Exo=0.05;
%%
for j=1:length(Time_Delay_Brain)
for jj=1:length(Time_Delay_Exo)
if Time_Delay_Exo(jj) ==0.05
n=11;
else
n=8;
end
%%
tau1=Time_Delay_Brain(j);tau2=Time_Delay_Exo(jj);
W = linspace(0, n*pi, 1000);omega=W;
Kpe=@(omega)J.*cos(omega.*tau2).*omega.^2 - KDb.*beta2.*omega.*sin(omega.*tau1 - omega.*tau2) + L.*cos(omega.*tau2).*g.*m - KPb.*beta2.*cos(omega.*tau1 - omega.*tau2);
Kde=@(omega)(omega.^2.*J.*sin(omega.*tau2) - KDb.*beta2.*omega.*cos(omega.*tau1 - omega.*tau2) + m.*g.*L.*sin(omega.*tau2) + KPb.*beta2.*sin(omega.*tau1 - omega.*tau2))./omega;
%%
D_Curve_PD_KPe=Kpe(omega);
D_Curve_PD_KDe=Kde(omega);
%%
plot(D_Curve_PD_KPe,D_Curve_PD_KDe,'color',[2*Time_Delay_Exo(jj) 2*Time_Delay_Brain(j) Time_Delay_Exo(jj) *Time_Delay_Brain(j)],'LineWidth', 0.2)
axis([0,18000,0,2500]);
hold on
end
hold on
end
plot([0 18000],[0 0],'color',[1 0 0],'LineWidth', 3)
plot([0 0],[0 2500],'color',[1 0 0],'LineWidth', 3)

Scott MacKenzie on 15 Aug 2021
Edited: Scott MacKenzie on 15 Aug 2021
x = D_Curve_PD_KPe;
y = D_Curve_PD_KDe;
cropLogical = x > 0;
x = x(cropLogical);
y = y(cropLogical);
% define vertices of polyshape and plot
x = [0 0 x x(end) 0];
y = [0 y(1) y 0 0];
ps = polyshape(x,y);
plot(ps, 'facecolor', 'y');
% compute and output area
a1 = polyarea(x,y);
fprintf('area = %.2f\n', a1);
Output:
area = 16482962.65 shahin sharafi on 16 Aug 2021
Thank you so much. It does work! You saved me

R2019a

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