# corona: Ridge Estimation by Corona Method In Rwave: Time-Frequency Analysis of 1-D Signals

 corona R Documentation

## Ridge Estimation by Corona Method

### Description

Estimate a (single) ridge from a time-frequency representation, using the corona method.

### Usage

```corona(tfrep, guess, tfspec=numeric(dim(tfrep)[2]), subrate=1,
temprate=3, mu=1, lambda=2 * mu, iteration=1000000, seed=-7,
stagnant=20000, costsub=1, plot=TRUE)
```

### Arguments

 `tfrep` Time-Frequency representation (real valued). `guess` Initial guess for the algorithm. `tfspec` Estimate for the contribution of the noise to modulus. `subrate` Subsampling rate for ridge estimation. `temprate` Initial value of temperature parameter. `mu` Coefficient of the ridge's second derivative in cost function. `lambda` Coefficient of the ridge's derivative in cost function. `iteration` Maximal number of moves. `seed` Initialization of random number generator. `stagnant` Maximum number of stationary iterations before stopping. `costsub` Subsampling of cost function in output. `plot` When set(default), some results will be shown on the display.

### Details

To accelerate convergence, it is useful to preprocess modulus before running annealing method. Such a preprocessing (smoothing and subsampling of modulus) is implemented in `corona`. The parameter subrate specifies the subsampling rate.

### Value

Returns the estimated ridge and the cost function.

 `ridge` 1D array (of same length as the signal) containing the ridge. `cost` 1D array containing the cost function.

### Warning

The returned cost may be a large array, which is time consuming. The argument costsub allows subsampling the cost function.

### References

See discussion in text of “Practical Time-Frequency Analysis”.

`icm`,`coronoid`,`snake`, `snakoid`.