how to plot sine and cosine waves in one graph ?

used for academic use

5 Comments

Write a program to plot the function sin(x) between 0≤x≤4π.
How can I plot cos(ax+b)
syms x b
a = randn()
a = -1.0804
f = cos(a*x + b);
fsurf(f, [-10 10 -2*pi 2*pi])
xlabel('x'); ylabel('b')

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 Accepted Answer

It sounds like the OP wants this in one graph (not subplotted)
t = 0:0.01:(2*pi);
x = cos(t);
y = sin(t);
plot(t,x,'k'); hold on;
plot(t,y,'r-.');
axis([0 2*pi -1.5 1.5])
legend('cos(t)','sin(t)','Location','NorthEast')

More Answers (4)

a = 10;
t = 0 : 0.01 : 10;
A = a*sin(t);
subplot(121),plot(t,A);
B = a*cos(t);
subplot(122),plot(t,B);

3 Comments

Thanks. What is subplot 121 and 122?
@Lee Johnson: syntax not supported by MATLAB. Looks like MatPlotLib to me.
The MATLAB subplot documentation gives this syntax:
subplot(m,n,p)
and explains what m, n, and p are. There is of course no point in simply copying this info here when you can read in the documentation (see link).
subplot 121 is archaic, no longer documented, but still works. It is interpreted as subplot(1, 2, 1)

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close all; clear all; clc;
t=[0:0.5:180]
x=sind(t);
plot(t,x),hold on
y=cosd(t);
plot(t,y)
legend('Sine wave','Cos wave')
hold on not needed
x=0:0.1:2*pi;
plot(x,sin(x),"b",x,cos(x),"g");
"b" and "g" - color

4 Comments

This is correct.
For old enough MATLAB (before R2017a) replace the "b" by 'b' and "g" by 'g'
Walter Roberson, thanks for the clarification about older versions! I did not know that.
I would not normally have mentioned a backwards compatibility like that now that we are 4 years on, but I suspect this question is getting read by people who are using old versions of MATLAB. (We are getting a rush of people using MATLAB from 2013 and 2015.)
You are absolutely right. This is very useful information, because not everyone has the latest versions, they are not required for simple tasks. Correct syntax - 50% success.

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