Next: Two-dimensional Geometric Shapes, Previous: Axis Configuration, Up: Two-Dimensional Plots [Contents][Index]

Octave can plot a function from a function handle, inline function, or
string defining the function without the user needing to explicitly
create the data to be plotted. The function `fplot`

also generates
two-dimensional plots with linear axes using a function name and limits
for the range of the x-coordinate instead of the x and y data. For
example,

fplot (@sin, [-10, 10], 201);

produces a plot that is equivalent to the one above, but also includes a legend displaying the name of the plotted function.

- Function File:
**fplot***(*`fn`,`limits`) - Function File:
**fplot***(…,*`tol`) - Function File:
**fplot***(…,*`n`) - Function File:
**fplot***(…,*`fmt`) - Function File:
*[*`x`,`y`] =**fplot***(…)* Plot a function

`fn`within the range defined by`limits`.`fn`is a function handle, inline function, or string containing the name of the function to evaluate.The limits of the plot are of the form

`[`

or`xlo`,`xhi`]`[`

.`xlo`,`xhi`,`ylo`,`yhi`]The next three arguments are all optional and any number of them may be given in any order.

`tol`is the relative tolerance to use for the plot and defaults to 2e-3 (.2%).`n`is the minimum number of points to use. When`n`is specified, the maximum stepsize will be

. More than`xhi`-`xlo`/`n``n`points may still be used in order to meet the relative tolerance requirement.The

`fmt`argument specifies the linestyle to be used by the plot command.If the first argument

`hax`is an axes handle, then plot into this axis, rather than the current axes returned by`gca`

.With no output arguments the results are immediately plotted. With two output arguments the 2-D plot data is returned. The data can subsequently be plotted manually with

`plot (`

.`x`,`y`)Example:

fplot (@cos, [0, 2*pi]) fplot ("[cos(x), sin(x)]", [0, 2*pi])

Programming Notes:

`fplot`

works best with continuous functions. Functions with discontinuities are unlikely to plot well. This restriction may be removed in the future.`fplot`

requires that the function accept and return a vector argument. Consider this when writing user-defined functions and use`.*`

,`./`

, etc. See the function`vectorize`

for potentially converting inline or anonymous functions to vectorized versions.

Other functions that can create two-dimensional plots directly from a
function include `ezplot`

, `ezcontour`

, `ezcontourf`

and
`ezpolar`

.

- Function File:
**ezplot***(*`f`) - Function File:
**ezplot***(*`f2v`) - Function File:
**ezplot***(*`fx`,`fy`) - Function File:
**ezplot***(…,*`dom`) - Function File:
**ezplot***(…,*`n`) - Function File:
**ezplot***(*`hax`, …) - Function File:
`h`=**ezplot***(…)* -
Plot the 2-D curve defined by the function

`f`.The function

`f`may be a string, inline function, or function handle and can have either one or two variables. If`f`has one variable, then the function is plotted over the domain`-2*pi <`

with 500 points.`x`< 2*piIf

`f2v`is a function of two variables then the implicit function

is calculated over the meshed domain`f`(`x`,`y`) = 0`-2*pi <=`

with 60 points in each dimension.`x`|`y`<= 2*piFor example:

ezplot (@(

`x`,`y`)`x`.^2 -`y`.^2 - 1)If two functions are passed as inputs then the parametric function

`x`=`fx`(`t`)`y`=`fy`(`t`)is plotted over the domain

`-2*pi <=`

with 500 points.`t`<= 2*piIf

`dom`is a two element vector, it represents the minimum and maximum values of both`x`and`y`, or`t`for a parametric plot. If`dom`is a four element vector, then the minimum and maximum values are`[xmin xmax ymin ymax]`

.`n`is a scalar defining the number of points to use in plotting the function.If the first argument

`hax`is an axes handle, then plot into this axis, rather than the current axes returned by`gca`

.The optional return value

`h`is a vector of graphics handles to the created line objects.**See also:**plot, ezplot3, ezpolar, ezcontour, ezcontourf, ezmesh, ezmeshc, ezsurf, ezsurfc.

- Function File:
**ezcontour***(*`f`) - Function File:
**ezcontour***(…,*`dom`) - Function File:
**ezcontour***(…,*`n`) - Function File:
**ezcontour***(*`hax`, …) - Function File:
`h`=**ezcontour***(…)* -
Plot the contour lines of a function.

`f`is a string, inline function, or function handle with two arguments defining the function. By default the plot is over the meshed domain`-2*pi <=`

with 60 points in each dimension.`x`|`y`<= 2*piIf

`dom`is a two element vector, it represents the minimum and maximum values of both`x`and`y`. If`dom`is a four element vector, then the minimum and maximum values are`[xmin xmax ymin ymax]`

.`n`is a scalar defining the number of points to use in each dimension.If the first argument

`hax`is an axes handle, then plot into this axis, rather than the current axes returned by`gca`

.The optional return value

`h`is a graphics handle to the created plot.Example:

f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2); ezcontour (f, [-3, 3]);

**See also:**contour, ezcontourf, ezplot, ezmeshc, ezsurfc.

- Function File:
**ezcontourf***(*`f`) - Function File:
**ezcontourf***(…,*`dom`) - Function File:
**ezcontourf***(…,*`n`) - Function File:
**ezcontourf***(*`hax`, …) - Function File:
`h`=**ezcontourf***(…)* -
Plot the filled contour lines of a function.

`f`is a string, inline function, or function handle with two arguments defining the function. By default the plot is over the meshed domain`-2*pi <=`

with 60 points in each dimension.`x`|`y`<= 2*piIf

`dom`is a two element vector, it represents the minimum and maximum values of both`x`and`y`. If`dom`is a four element vector, then the minimum and maximum values are`[xmin xmax ymin ymax]`

.`n`is a scalar defining the number of points to use in each dimension.`hax`is an axes handle, then plot into this axis, rather than the current axes returned by`gca`

.The optional return value

`h`is a graphics handle to the created plot.Example:

f = @(x,y) sqrt (abs (x .* y)) ./ (1 + x.^2 + y.^2); ezcontourf (f, [-3, 3]);

- Function File:
**ezpolar***(*`f`) - Function File:
**ezpolar***(…,*`dom`) - Function File:
**ezpolar***(…,*`n`) - Function File:
**ezpolar***(*`hax`, …) - Function File:
`h`=**ezpolar***(…)* -
Plot a 2-D function in polar coordinates.

The function

`f`is a string, inline function, or function handle with a single argument. The expected form of the function is

. By default the plot is over the domain`rho`=`f`(`theta`)`0 <=`

with 500 points.`theta`<= 2*piIf

`dom`is a two element vector, it represents the minimum and maximum values of`theta`.`n`is a scalar defining the number of points to use in plotting the function.`hax`is an axes handle, then plot into this axis, rather than the current axes returned by`gca`

.The optional return value

`h`is a graphics handle to the created plot.Example:

ezpolar (@(t) sin (5/4 * t), [0, 8*pi]);