# plot the fundamental harmonic wave

조회 수: 9 (최근 30일)
hamid k 2023년 11월 19일
답변: Mathieu NOE 2023년 11월 23일
Hello everyone. I have exported data to an Excel spreadsheet where the x-axis is represented by theta (in radians). How can I plot the fundamental harmonic wave from this wave data?
##### 댓글 수: 6이전 댓글 4개 표시이전 댓글 4개 숨기기
hamid k 2023년 11월 23일
You can find the attached data and code files here.
Mathieu NOE 2023년 11월 23일
see my answer below

댓글을 달려면 로그인하십시오.

### 채택된 답변

Mathieu NOE 2023년 11월 23일
hello again
so this is it, we do a single frequency DFT (aka order extraction) at the second harmonic (as we have two period of signal for theta ranging from 0 to 2*pi
result :
code :
%Load Excel file
data = readmatrix('Book1.xlsx'); % theta(Rad) Br(T)
%Extract theta and y columns
theta = data(:,1); % theta (0 - 2pi)
y = data(:,2); % y data
%%%%%%%%%%%%% main code %%%%%%%%%%%%%%%%%
% 2nd order extraction (DFT)
order = 2;
% model fit : X = A*cos(order*theta) + B*sin(order*theta) + C
C = mean(y);
y = y-C;
n = numel(theta);
A = 2/n*trapz(y.*cos(order*theta));
B = 2/n*trapz(y.*sin(order*theta));
yfit = A*cos(order*theta) + B*sin(order*theta) + C;
% plot
figure(1),
plot(theta, y, 'b',theta, yfit, 'r')
legend('data','model fit');

댓글을 달려면 로그인하십시오.

### 추가 답변 (1개)

Sulaymon Eshkabilov 2023년 11월 20일
Here are two MATLAB fcns (bandpass() and fft()) which can be applied to solve your exercise.

댓글을 달려면 로그인하십시오.

### 카테고리

Help CenterFile Exchange에서 Transforms에 대해 자세히 알아보기

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by