inla.mesh.basis {INLA} | R Documentation

## Basis functions for inla.mesh

### Description

Calculate basis functions on a 1d or 2d `inla.mesh`

### Usage

    inla.mesh.basis(mesh,
                    type="b.spline",
                    n=3,
                    degree=2,
                    knot.placement="uniform.area",
                    rot.inv=TRUE,
                    boundary="free",
                    free.clamped=TRUE,
                    ...)

### Arguments

`mesh` | An `inla.mesh.1d` or `inla.mesh` object.
`type` | `b.spline` (default) for B-spline basis functions, `sph.harm` for spherical harmonics (available opnly for meshes on the sphere)
`n` | For B-splines, the number of basis functions in each direction (for 1d meshes `n` must be a scalar, and for planar 2d meshes a 2-vector). For spherical harmonics, `n` is the maximal harmonic order.
`degree` | Degree of B-spline polynomials. See `inla.mesh.1d`.
`knot.placement` | For B-splines on the sphere, controls the latitudinal placements of knots. `"uniform.area"` (default) gives uniform spacing in sin(latitude), `"uniform.latitude"` gives uniform spacing in latitudes.
`rot.inv` | For spherical harmonics on a sphere, `rot.inv=TRUE` gives the rotationally invariant subset of basis functions.
`boundary` | Boundary specification, default is free boundaries. See `inla.mesh.1d` for more information.
`free.clamped` | If `TRUE` and `boundary` is `"free"`, the boundary basis functions are clamped to 0/1 at the interval boundary by repeating the boundary knots.
`...` |

### Author(s)

Finn Lindgren finn.lindgren@gmail.com

### See Also

`inla.mesh.1d` `inla.mesh.2d`

### Examples

    n = 100
    loc = matrix(runif(n*2), n, 2)
    mesh = inla.mesh.2d(loc, max.edge=0.05)
    basis = inla.mesh.basis(mesh, n=c(4,5))

    proj = inla.mesh.projector(mesh)
    image(proj$x, proj$y, inla.mesh.project(proj, basis[,7]))

    if (require(rgl)) {
      plot(mesh, rgl=TRUE, col=basis[,7], draw.edges=FALSE, draw.vertices=FALSE)
    }

[Package INLA version 18.07.12 Index]