rcomparithm {compositions} | R Documentation |

## Arithmetic operations for compositions in a real geometry

### Description

The real compositions form a manifold of the real vector space. The induced operations +,-,*,/ give results valued in the real vector space, but possibly outside the simplex.

### Usage

```
convex.rcomp(x,y,alpha=0.5)
## Methods for class "rcomp"
## x+y
## x-y
## -x
## x*r
## r*x
## x/r
```

### Arguments

`x` |
an rcomp composition or dataset of compositions |

`y` |
an rcomp composition or dataset of compositions |

`r` |
a numeric vector of size 1 or nrow(x) |

`alpha` |
a numeric vector of size 1 or nrow(x) with values between 0 and 1 |

### Details

The functions behave quite like `+.rmult`

.

The convex combination is defined as: `x*alpha + (1-alpha)*y`

### Value

`rmult`

-objects containing the given operations on the simplex
as subset of the `R^D`

. Only the convex combination
`convex.rcomp`

results in an `rcomp`

-object again, since
only this operation is closed.

### Note

For `*`

the arguments x and y can be exchanged.

### Author(s)

K.Gerald v.d. Boogaart http://www.stat.boogaart.de

### See Also

`+.rmult`

, `+.acomp`

,`cpt`

, `rcomp`

, `rmult`

### Examples

```
rcomp(1:5)* -1 + rcomp(1:5)
data(SimulatedAmounts)
cdata <- rcomp(sa.lognormals)
plot( tmp <- (cdata-mean(cdata))/msd(cdata) )
class(tmp)
mean(tmp)
msd(tmp)
var(tmp)
plot(convex.rcomp(rcomp(c(1,1,1)),sa.lognormals,0.1))
```

*compositions*version 2.0-8 Index]