Keep getting an error with trapz. Please help

clear
close all
clc

dt = 0.01; 
t = 4; 
T = 0:dt:t; 

% First Quarter 
r1 = 0:dt:t/4  ;
p1 = sin(pi.*r1)  ; 
hold on

figure(1)

% Second Quarter
r2 = t/4:dt:t/2;
p2 = 0*r2;

% Third Quearter
r3 = t/2:dt:(3*t)/4;
p3 = 1.^r3

p3 = 1×101

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

% Fourth Quarter
r4 = (3*t)/4:dt:t

r4 = 1×101

3.0000 3.0100 3.0200 3.0300 3.0400 3.0500 3.0600 3.0700 3.0800 3.0900 3.1000 3.1100 3.1200 3.1300 3.1400 3.1500 3.1600 3.1700 3.1800 3.1900 3.2000 3.2100 3.2200 3.2300 3.2400 3.2500 3.2600 3.2700 3.2800 3.2900

p4 = 0*r4;

time = [r1 r2 r3 r4]

time = 1×404

0 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600 0.0700 0.0800 0.0900 0.1000 0.1100 0.1200 0.1300 0.1400 0.1500 0.1600 0.1700 0.1800 0.1900 0.2000 0.2100 0.2200 0.2300 0.2400 0.2500 0.2600 0.2700 0.2800 0.2900

gigi = [p1 p2 p3 p4]

gigi = 1×404

0 0.0314 0.0628 0.0941 0.1253 0.1564 0.1874 0.2181 0.2487 0.2790 0.3090 0.3387 0.3681 0.3971 0.4258 0.4540 0.4818 0.5090 0.5358 0.5621 0.5878 0.6129 0.6374 0.6613 0.6845 0.7071 0.7290 0.7501 0.7705 0.7902

figure(2)
plot(time,gigi,'r')
grid on
hold off

% Saif Bet
ribua = power(gigi,2)

ribua = 1×404

0 0.0010 0.0039 0.0089 0.0157 0.0245 0.0351 0.0476 0.0618 0.0778 0.0955 0.1147 0.1355 0.1577 0.1813 0.2061 0.2321 0.2591 0.2871 0.3159 0.3455 0.3757 0.4063 0.4373 0.4686 0.5000 0.5314 0.5627 0.5937 0.6243

baba = trapz(T,ribua)

Error using trapz
Point spacing must be a scalar specifying uniform spacing or a vector of x-coordinates for each data point.

Answer 1

[Torsten]

baba = trapz(time,ribua)

instead of

baba = trapz(T,ribua)

[David]

Thank you for fast response !

Will it integrate between 0 to 4 ?

The qeustion is will it include zero ?

And what does it mean the "time" ?

Thank you !

[Torsten]

r1 goes from 0 to 1, r2 goes from 1 to 2, r3 goes from 2 to 3, r4 goes from 3 to 4.

The function is defined piecewise in p1, p2, p3 and p4 corresponding to the r1, r2, r3 and r4.

Thus the integral of the function over [0 4] is

baba = trapz(r1,p1.^2) + trapz(r2,p2.^2) + trapz(r3,p3.^2) + trapz(r4,p4.^2)

which equals

baba = trapz(time,ribua)