`errbar` documentation

This function plots vertical or horizontal errorbars. Error bars may be symmetic or asymmetric about their data points.

## Contents

## Syntax

errbar(x,y,E) errbar(x,y,L,U) errbar(...,'horiz') errbar(...,LineSpec) h = errbar(...)

## Description

`errbar(x,y,E)` plots vertical lines of length `2*E` centered on x,y. `E` may be a scalar or a vector matching the size of `x`.

`errbar(x,y,L,U)` specifies different lower and upper bounds of error bars. `L` and `U` may be mixed vector and scalar.

`errbar(...,'horiz')` plots error bars horizontally.

`errbar(...,LineSpec)` specifies line type.

`h = errbar(...)` returns a handle `h` of plotted error bars.

## Usage note

This function is very similar to Matlab's built-in `errorbar` function, but the two functions differ in the following ways:

`errbar`supports horizontal error bars with the simple inclusion of the`'horiz'`tag.

`errbar`does not plot perpendicular lines at the ends of error bars, because in my experience, those lines tend to be garrish and distracting, and they do not automatically rescale when zooming. If you'd like perpendicular lines at the ends of your errbars, you can get a similar effect by specifying a LineStyle`'+-'`.

`errbar`does not plot markers at datapoints x,y. This is intentional, because it's rare that I want my error bars to have the same linewidth and bold coloring

`errbar`allows error values to be entered as a scalar, whereas Matlab's built-in`errorbar`function forces users to populate an array of redundant values.

## Example 1: Simple vertical error bars

Stealing this example from the documentation for Matlab's built-in `errorbar` function:

X = 0:pi/10:pi; Y = sin(X); E = std(Y); plot(X,Y,'bo-','linewidth',3) hold on errbar(X,Y,E) % <- Here's the errbar function

## Example 2: Formatted error bars

Formatting with `errbar` is as simple as any LineSpec formatting. Each error bar is made of only two endpoints and a line connecting them, so any marker properties will be applied to the ends of the error bars. Here's a simple red error bar with plus signs at its ends:

x = 1:5; y = sin(x); figure plot(x,y,'bo','markersize',10) hold on errbar(x,y,.2,'r+-')

## Example 3: Horizontal error bar

Now we'll add horizontal error bars to the plot above. For the lower bound we'll specify a scalar, and for the upper bound some random numbers. Make the error bars thick and black with `'k','linewidth',3` :

xLowerUncertainty = .1; xUpperUncertainty = (2*rand(size(x))).^2; errbar(x,y,xLowerUncertainty,xUpperUncertainty,'k','linewidth',3,'horiz')

## Author Info

The `errbar` function was written by Chad A. Greene of the University of Texas at Austin's Institute for Geophysics, April 2015.