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errorbar

Plot error bars along curve

Syntax

errorbar(Y,E)
errorbar(X,Y,E)
errorbar(X,Y,L,U)
errorbar(...,LineSpec)
h = errorbar(...)

Description

Error bars show the confidence intervals of data or the deviation along a curve.

errorbar(Y,E) plots Y and draws an error bar at each element of Y. The error bar is a distance of E(i) above and below the curve so that each bar is symmetric and 2*E(i) long.

errorbar(X,Y,E) plots Y versus X with symmetric error bars 2*E(i) long. X, Y, E must be the same size. When they are vectors, each error bar is a distance of E(i) above and below the point defined by (X(i),Y(i)). When they are matrices, each error bar is a distance of E(i,j) above and below the point defined by (X(i,j),Y(i,j)).

errorbar(X,Y,L,U) plots X versus Y with error bars L(i)+U(i) long specifying the lower and upper error bars. X, Y, L, and U must be the same size. When they are vectors, each error bar is a distance of L(i) below and U(i) above the point defined by (X(i),Y(i)). When they are matrices, each error bar is a distance of L(i,j) below and U(i,j) above the point defined by (X(i,j),Y(i,j)).

errorbar(...,LineSpec) uses the color and line style specified by the string 'LineSpec'. The color is applied to the data line and error bars. The linestyle and marker are applied to the data line only. See linespec for examples of styles.

h = errorbar(...) returns handles to the errorbarseries objects created. errorbar creates one object for vector input arguments and one object per column for matrix input arguments. See errorbarseries properties for more information.

When the arguments are all matrices, errorbar draws one line per matrix column. If X and Y are vectors, they specify one curve.

Examples

expand all

Symmetric Error Bars

Draw symmetric error bars that are two standard deviation units in length.

```x = 0:pi/10:pi;
y = sin(x);
e = std(y)*ones(size(x));

figure
errorbar(x,y,e)
```

Change Error Bar Marker and Color

Load the count data set to get the three-column matrix count that contains traffic volume for three street locations over the course of a day. Compute the mean of count for each row.

```load count.dat;
y = mean(count,2);
```

Compute the standard deviation of count for each row and normalize by the number of elements in the sample by setting the second input argument to 1.

```e = std(count,1,2);
```

Plot the computed average traffic volume, y, and the computed standard deviations, e, for the three street locations. Set the LineSpec to specify a red color, cross markers, and no line.

```figure
errorbar(y,e,'rx')
```