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# rooteig() - Signal Processing

```[w,pow] = rooteig(x,p) estimates
the frequency content in the time samples of a signal x,
and returns w, a vector of frequencies in rad/sample,
and the corresponding signal power in the vector pow in
units of power, such as volts^2. The input signal x is
specified either as:A row or column vector representing one observation
of the signalA rectangular array for which each row of x represents
a separate observation of the signal (for example, each row is one
output of an array of sensors, as in array processing), such that x'*x is
an estimate of the correlation matrix Note

You can use the output of corrmtx to
generate such an array x.You can specify the second input argument p as
either:A scalar integer. In this case, the signal subspace
dimension is p.A two-element vector. In this case, p(2),
the second element of p, represents a threshold
that is multiplied by λmin, the smallest
estimated eigenvalue of the signal's correlation matrix. Eigenvalues
below the threshold λmin*p(2) are
assigned to the noise subspace. In this case, p(1) specifies
the maximum dimension of the signal subspace.The extra threshold parameter in the second entry in p provides
you more flexibility and control in assigning the noise and signal
subspaces. The length of the vector w is the computed
dimension of the signal subspace. For real-valued input data x,
the length of the corresponding power vector pow is
given by length(pow) = 0.5*length(w)
For complex-valued input data x, pow and w have
the same length.[f,pow] = rooteig(...,fs) returns
the vector of frequencies f calculated in Hz.
You supply the sampling frequency fs in Hz. If
you specify fs with the empty vector [],
the sampling frequency defaults to 1 Hz.[w,pow] = rooteig(...,'corr') forces
the input argument x to be interpreted as a correlation
matrix rather than a matrix of signal data. For this syntax, you must
supply a square matrix for x, and all of its eigenvalues
must be nonnegative. Note

You can place the string 'corr' anywhere
after p.```

### Syntax

`[w,pow] = rooteig(x,p)[f,pow] = rooteig(...,fs)[w,pow] = rooteig(...,'corr')`

### Example

`length(pow) = 0.5*length(w)`