5.7: Matlab Functions with No Inputs

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Carey Smith
Oxnard College

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By Carey A. Smith

Functions can have outputs, even though they have no input arguments.

These are some built-in Matlab functions with no inputs:

date % Try it

datetime % Try it

The function definition of such a file would be like this:

function [date1] = date()

An interesting Matlab function with no inputs is:

This is used as a constant, but it is an actual function. You could define your own functions for constants such as Avogadro’s number, the universal gravitational constant, the speed of light, or a parsec’s distance.

Example \(\PageIndex{1}\) draw_ellipse.m

This example is a function (draw to draw a circle or an ellipse.

It has 3 input variables, but no output variable.

A figure should be opened before calling this function.

function [ ] = draw_ellipse(rx, ry, color) % This function draws an ellipse or a circle % by drawing short lines between 32 point on a circle % The inputs are: % rx = width (x direction) % height (y direction) % color: One these: 'b', 'c', 'g', 'k', 'r', or 'y' % There is no returned value. dth = pi/16; % (radians) The angle between points theta = 0: dth : 2*pi; x1 = rx*cos(theta); y1 = ry*sin(theta); plot(x1,y1,color,'LineWidth',4) end

After calling the function, the user should useaxis equal so that the plot has the correct shape.

This script (draw_ellipse_example.m) demonstrates the draw_ellipse function

figure; rx = 3 ry = 2; draw_ellipse(rx, ry, 'b') axis equal grid on; title('draw\_ellipse Example')

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Solution

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