# How to write the first line of a function?

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I have a matrix of data, X. I need to create a function that will plot all columns of this data in a given number of different figures. The function should be called composite_plot. The function should have two inputs, the first will be the data, X, the second input will be the number of figures to be produced. For example, a call to composite_plot(X,10), should produce ten figures.

How would I write the first line of the function? I've never written a function before and so don't really know how many inputs and outputs to have or what to call them. I know it should be set out something like this

function[?]=composite_plot(?,?)

Can anyone help?

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Image Analyst
on 9 Mar 2015

### Answers (1)

Iain
on 13 Jan 2015

Edited: Iain
on 13 Jan 2015

The first line of a function should look something like this:

function [a b c] = something(a, b, c) % 3 inputs, 3 outputs

function something(a,b) % 2 inputs, 0 outputs

function varargout = something(varargin) %any number of inputs and outputs

function a = something(varargin) % 1 output, any number of inputs.

function [a b c d varargout] = something % no inputs, 4 outputs MINIMUM

function something(a,b,c,d,varargin) % no outputs, 4 inputs MINIMUM.

You should use sensible variable names, instead of random letters like I did. varargin and varargout are more advanced features that let you deal with variable numbers of inputs and outputs. nargin and nargout are what tells you how many inputs & outputs you have if you want to use them.

You should also remember that any input or output can be an array.

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