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# Documentation

### Contents

Add lifting steps to lifting scheme

## Description

LSN = addlift(LS,ELS) returns the new lifting scheme LSN obtained by appending the elementary lifting step ELS to the lifting scheme LS.

LSN = addlift(LS,ELS,'begin') prepends the specified elementary lifting step.

ELS is either a cell array (see lsinfo)

```{TYPEVAL, COEFS, MAX_DEG}
```

or a structure (see liftfilt)

```struct('type',TYPEVAL,'value',LPVAL)
```

with

```LPVAL = laurpoly(COEFS, MAX_DEG)
```

LSN = addlift(LS,ELS,'end') is equivalent to addfilt(LS,ELS).

If ELS is a sequence of elementary lifting steps, stored in a cell array or an array of structures, then each of the elementary lifting steps is added to LS.

## Add Primal Lifting Step

This example shows how to start with the Haar lifting scheme and add a primal lifting step.

```LSbegin = liftwave('haar');
```

Display the lifting scheme.

```displs(LSbegin);
```
```LSbegin = {...
'd'             [ -1.00000000]  [0]
'p'             [  0.50000000]  [0]
[  1.41421356]  [  0.70710678]  []
};
```

Create a primal lifting step.

```pstep = { 'p', [-1 2 -1]/4 , 1 };
```

Add the primal lifting step.

```LSend = addlift(LSbegin,pstep);
```

Display the final lifting scheme.

```displs(LSend);
```
```LSend = {...
'd'             [ -1.00000000]                          [0]
'p'             [  0.50000000]                          [0]
'p'             [ -0.25000000  0.50000000 -0.25000000]  [1]
[  1.41421356]  [  0.70710678]                          []
};
```