normspec

Normal density plot shading between specifications

Syntax

p = normspec(specs)

p = normspec(specs,mu,sigma)

p = normspec(specs,mu,sigma,region)

p = normspec(ax,___)

[p,h] = normspec(___)

Description

p = normspec(specs) plots the standard normal density, shading the portion inside the specification limits given by the two-element vector specs, and returns the probability p of the shaded area. If spec has no lower limit, then set specs(1) to –Inf; if spec has no upper limit, then set specs(2) to Inf.

p = normspec(specs,mu,sigma) uses a normal density with parameters mu and sigma.

p = normspec(specs,mu,sigma,region) specifies the shading region as either 'inside' or 'outside' the specification limits. The default is 'inside'.

p = normspec(ax,___) plots into the axes specified by ax instead of the current axes (gca) using any of the input argument combinations in the previous syntaxes. (since R2024a)

[p,h] = normspec(___) also returns a column vector of chart line objects h. Use h to modify properties of a specific chart line after you create the chart. For a list of properties, see Line Properties.

Examples

Create Standard Normal Density Plot Shading Inside of Limits

Create a standard normal density plot, shading the portion inside the specification limits [-1,1].

p = normspec([-1,1])

p = 
0.6827

Create Normal Density Plot Shading Outside of Limits

Create a normal density plot, shading the portion outside the specification limits.

For example, consider a production process that fills cans of paint. The average amount of paint in any can is 1 gallon, but variability in the process produces a standard deviation of 2 ounces (2/128 gallons). Create a normal density plot, shading the portion corresponding to the probability that the cans will be filled under specification by 3 or more ounces.

p = normspec([1-3/128,Inf],1,2/128,'outside')

p = 
0.0668

Input Arguments

specs — Specification limits

two-element numeric vector

Specification limits, specified as a two-element numeric vector. Set specs(1) to –Inf if there is no lower limit; set specs(2) to Inf if there is no upper limit.

Data Types: single | double

mu — Mean

0 (default) | scalar value

Mean of the normal distribution, specified as a scalar value.

Data Types: single | double

sigma — Standard deviation

1 (default) | positive scalar value

Standard deviation of the normal distribution, specified as a positive scalar value.

Data Types: single | double

region — Shading region

'inside' (default) | 'outside'

Shading region, specified as either 'inside' or 'outside'. The function normspec shades the region either 'inside' or 'outside' the specification limits.

ax — Target axes

Axes object

Since R2024a

Target axes, specified as an Axes object. If you do not specify the axes, then normspec uses the current axes (gca).

Output Arguments

p — Probability of shaded area

nonnegative scalar value

Probability of the shaded area, returned as a nonnegative scalar value.

h — One or more chart line objects

scalar | vector

One or more chart line objects, returned as a scalar or vector. These objects are unique identifiers that you use to query and modify properties of a specific chart line. For a list of properties, see Line Properties.

Version History

Introduced before R2006a

R2024a: Specify target axes

Specify the target axes for the plot by using the ax input argument.