# fsurfht

Interactive contour plot

## Syntax

```fsurfht(fun,xlims,ylims) fsurfht(fun,xlims,ylims,p1,p2,p3,p4,p5) ```

## Description

`fsurfht(fun,xlims,ylims)` is an interactive contour plot of the function specified by the text variable `fun`. The x-axis limits are specified by `xlims` in the form `[xmin xmax]`, and the y-axis limits are specified by `ylims` in the form `[ymin ymax]`.

`fsurfht(fun,xlims,ylims,p1,p2,p3,p4,p5)` allows for five optional parameters that you can supply to the function `fun`.

The intersection of the vertical and horizontal reference lines on the plot defines the current x value and y value. You can drag these reference lines and watch the calculated z-values (at the top of the plot) update simultaneously. Alternatively, you can type the x value and y value into editable text fields on the x-axis and y-axis.

## Examples

Plot the Gaussian likelihood function for the `gas.mat` data.

```load gas ```

Create a function containing the following commands, and name it `gauslike.m`.

```function z = gauslike(mu,sigma,p1) n = length(p1); z = ones(size(mu)); for i = 1:n z = z .* (normpdf(p1(i),mu,sigma)); end ```

The `gauslike` function calls `normpdf`, treating the data sample as fixed and the parameters µ and σ as variables. Assume that the gas prices are normally distributed, and plot the likelihood surface of the sample.

```fsurfht('gauslike',[112 118],[3 5],price1) ``` The sample mean is the x value at the maximum, but the sample standard deviation is not the y value at the maximum.

```mumax = mean(price1) mumax = 115.1500 sigmamax = std(price1)*sqrt(19/20) sigmamax = 3.7719 ```
Introduced before R2006a