Is it possible to use the trapz function to calculate the integrated value for each point of a data set?

Question

C Smyth 2018-7-12

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410037-is-it-possible-to-use-the-trapz-function-to-calculate-the-integrated-value-for-each-point-of-a-data

评论： Star Strider 2018-7-12

I have a column of data that plots a sin wave. I want to know the area under the curve at a given point or of a set number of samples, for example, a time vector.

This data is plotted against time with every 100 data points representing one second.

Is it possible to calculate the area under the curve for every 100 points? I want to end up with a sin wave with the integrated values i.e. how the area under the curve changes over time.

Is this possible? or is there another/better way to do this?

Thank you in advance

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2018-7-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/410037-is-it-possible-to-use-the-trapz-function-to-calculate-the-integrated-value-for-each-point-of-a-data#answer_328578

在 MATLAB Online 中打开

I am not certain how you are generating your signal.

One option is to use the reshape (link) function with your signal:

t = linspace(0, 2*pi, 10000);
s = sin(t);
sr = reshape(s(:), 100, []);
int_sr = trapz(sr);

2 个评论
显示无隐藏无

C Smyth 2018-7-12

The signal is an impedance breathing signal recorded from a person at 100 Hz. The length of the signal is 6787.

Star Strider 2018-7-12

在 MATLAB Online 中打开

Try this:

Fs = 100;                                                   % Sampling Frequency (Hz)
N = 6767;                                                   % Number Of Samples
t = linspace(0, N, N)/Fs;                                   % Time Vector
s = sin(2*pi*t/75);                                         % Signal
L = numel(s);                                               % Signal Length
sr = reshape(s(1:fix(L/Fs)*Fs)', 100, []);                  % Reshape Signal Vector
int_sr = trapz(sr);
figure(1)
plot(t, s*100)
hold on
stairs(t(1:Fs:end-Fs), int_sr)
hold off