Matlab

  %实例2： 输出1，0.9，。。。。0；这10个数。
  for a = 1.0: -0.1: 0.0
    % 打印变量
    disp(a)
  end

pkg install -forge msh

clc
close all
clear all
try
  pkg load matgeom;
catch
  error('Could not load Octave Forge package: matgeom');
end

t = linspace(0, 2*pi, 200);
figure; hold on;
plot(t, sin(t));
drawArrow([2 -1 pi 0], .1, .05, .5);

disp("Hello World");

%%
%% test.m
%%
clear all
clc

fo = 4; %frequency of the sine wave
Fs = 100; %sampling rate
Ts = 1/Fs; %sampling time interval
t = 0:Ts:1-Ts; %sampling period
n = length(t); %number of samples
y = 2*sin(2*pi*fo*t); %the sine curve

subplot(3,1,1);
plot(t,y)
xlabel('time (seconds)')
ylabel('y(t)')
title('Sample Sine Wave')
grid

subplot(3,1,2);
YfreqDomain = fft(y); %take the fft of our sin wave, y(t)

stem(abs(YfreqDomain)); %use abs command to get the magnitude
%similary, we would use angle command to get the phase plot!
%we'll discuss phase in another post though!

xlabel('Sample Number')
ylabel('Amplitude')
title('Using the Matlab fft command')
grid
axis([0,100,0,120])

subplot(3, 1, 3);
[YfreqDomain, freqRange] = centeredFFT(y, Fs);
stem(freqRange, abs(YfreqDomain));
xlabel('Hz')
ylabel("Amplitude")
grid
axis([-6,6,0,1.5])

%%
%% centeredFFT.m
%%
function [X,freq]=centeredFFT(x,Fs)
    %this is a custom function that helps in plotting the two-sided spectrum
    %x is the signal that is to be transformed
    %Fs is the sampling rate

    N=length(x);

    %this part of the code generates that frequency axis
    if mod(N,2)==0
    k=-N/2:N/2-1; % N even
    else
    k=-(N-1)/2:(N-1)/2; % N odd
    end
    T=N/Fs;
    freq=k/T; %the frequency axis

    %takes the fft of the signal, and adjusts the amplitude accordingly
    X=fft(x)/N; % normalize the data
    X=fftshift(X); %shifts the fft data so that it is centered
end