# Bivariate Linear Interpolation

`stats-interpLinear.Rd`

Bivariate Linear Interpolation. Options are available for gridded and pointwise interpolation.

## Arguments

- x, y, z
for

`linearInterp`

the arguments`x`

and`y`

are two numeric vectors of grid pounts, and`z`

is a numeric matrix or any other rectangular object which can be transformed by the function`as.matrix`

into a matrix object. For`linearInterpp`

we consider either three numeric vectors of equal length or if`y`

and`z`

are NULL, a list with entries`x`

,`y`

,`z`

, or named data frame with`x`

in the first,`y`

in the second, and`z`

in the third column.- gridPoints
an integer value specifying the number of grid points in

`x`

and`y`

direction.- xo, yo
for

`linearInterp`

two numeric vectors of data points spanning the grid, and for`linearInterpp`

two numeric vectors of data points building pairs for pointwise interpolation.

## Value

for `linearInterp`

, a list with at least three entries,

`x`

, `y`

and `z`

. The returned values, can be used
directly in `persp`

and `contour`

3D plotting methods.

for `linearInterpp`

, a `data.frame`

with columns

`"x"`

, `"y"`

, and `"z"`

.

## Examples

```
## linearInterp -
# Linear Interpolation:
if (requireNamespace("interp")) {
set.seed(1953)
x = runif(999) - 0.5
y = runif(999) - 0.5
z = cos(2*pi*(x^2+y^2))
ans = linearInterp(x, y, z, gridPoints = 41)
persp(ans, theta = -40, phi = 30, col = "steelblue",
xlab = "x", ylab = "y", zlab = "z")
contour(ans)
}
```