# pvinfo

Describe parameter vector specified with `pvec`

## Syntax

```[typ,k,nv] = pvinfo(pv)
[pmin,pmax,dpmin,dpmax] = pvinfo(pv,'par',j)
vj = pvinfo(pv,'par',j)
p = pvinfo(pv,'eval',c)
```

## Description

`pvinfo` retrieves information about a vector p = (p1, . . ., pn) of real parameters declared with `pvec` and stored in `pv`. The command `pvinfo(pv)` displays the type of parameter vector (`'box'` or `'pol'`), the number n of scalar parameters, and for the type `'pol'`, the number of vertices used to specify the parameter range.

For the type `'box'`:

```[pmin,pmax,dpmin,dpmax] = pvinfo(pv,'par',j) ```

returns the bounds on the value and rate of variations of the j-th real parameter pj. Specifically,

$p\mathrm{min}\le {p}_{j}\left(t\right)\le p\mathrm{max},dp\mathrm{min}\le \frac{d{p}_{j}}{dt}\le dp\mathrm{max}$

For the type `'pol'`:

```pvinfo(pv,'par',j) ```

returns the j-th vertex of the polytope of Rn in which p ranges, while

```pvinfo(pv,'eval',c) ```

returns the value of the parameter vector p given its barycentric coordinates `c` with respect to the polytope vertices (V1, . . .,Vk). The vector `c` must be of length k and have nonnegative entries. The corresponding value of p is then given by

$p=\frac{\sum _{i=1}^{k}{c}_{i}{V}_{i}}{\sum _{i=1}^{k}{c}_{i}}$

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