MATLAB: Sinusoidal Random Vector question

frequencyMATLAB

I want to create a vector of the same length as another vector called variable t. Typically, I would just use linspac; however, I do not want a linear regression. preferably, I'd like to make a sinusoidal regression if at all possible… if not any non-linear regression will do. What's the best way to go about this?

Best Answer

This is just a guess.

f1 = 4500;
f2 = 4700;
x = (sin(linspace(-pi/2,pi/2,20))+1)/2*(f2-f1) + f1;
plot(x)

But it is not random. Do you also want something that is random? You did say random in the original question, but in the comment, you said nothing about randomness.

Related Solutions

MATLAB: How do i do this in MATLAB

>> size(t1)
ans =
           1       20000
>> size(t2)
ans =
           1       25000

Your x1 is the same size as t1, and your x2 is the same size as t2. x1+x2 is therefore attempting to add a vector of length 20000 and a vector of length 25000.

You are using the wrong approach.

f1 = 4000;        %sinusoidal frequency

A1 = 0.2;         %amplitude

f2 = 5000;        %sinusoidal frequency
A2 = 0.25;       %amplitude
secs = 5;
N = lcm(f1*secs, f2*secs);   %lowest common multiple
t = linspace(0, secs, N+1);
t(end) = [];
x1 = A1*cos(2*pi*f1*t)+randn(size(t));
x2 = A2*cos(2*pi*f2*t)+randn(size(t));

You should consider whether the randn should be at full magnitude or should be multiplied by A1 or A2 . As it is you have 5 times as much noise as you have signal for x1.

You do not really need the full lcm() samples over 5 seconds, but using the lcm() ensures that there are an exact integer number of cycles for each of f1 and f2 in those 5 seconds.

I am, though, seeing some clipping in cos(2*pi*f1*t) that I cannot quite explain at the moment.

MATLAB: Create a row Matrix

This is one option:

r = 0.5;
idx = randperm(20, ceil(r*20));
rv = zeros(1,20);
rv(idx) = 1;

The logic is relatively straightforward: ‘idx’ uses rendperm to generate a matrix of index positions, then generates ‘rv’ and uses ‘idx’ to determine the r*20 values that are set to 1.

With r = 0.5, this yields:

rv =
    Columns 1 through 17
       0     1     0     0     1     0     0     1     1     1     1     0     1     0     0     1     1
    Columns 18 through 20
       1     0     0

Best Answer

Related Solutions

MATLAB: How do i do this in MATLAB

MATLAB: Create a row Matrix

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