I need to find 10000 ramdom # in the range of (0.078,0.0078) for mass and (2, 0.1) for diameter. Then calculate the density of the 10k and do a histogram of them. Can anybody help me please?. This is what I got so far but is not working.

1 view (last 30 days)
clc, clear
%samples for the mass
a1 = 0.078;
b1 = 0.0078;
m = b1.*randn(10000,1)+a1;
%samples for the diameter
a2 = 2;
b2 = 0.1;
d = b2.*randn(10000,1)+a2;
%finding the density
density = (m/((4/3).*pi.*(d/2).*(d/2).*(d/2)));

Answers (2)

Azzi Abdelmalek
Azzi Abdelmalek on 29 Aug 2016
You mean in the range of [0.0078 0.078] not [0.078, 0.0078], because 0.0078 is less then 0.078.
a1 = 0.078;
b1 = 0.0078;
m = a1.*rand(10000,1)+b1
  1 Comment
John D'Errico
John D'Errico on 29 Aug 2016
Edited: John D'Errico on 29 Aug 2016
Please stop adding answers every time you want to make a simple comment. There is a link for comments. Use it.
Moved answer by Shirly into a comment:
"the values for my density are zeros and the histogram is blank"

Sign in to comment.

Image Analyst
Image Analyst on 30 Aug 2016
Try this:
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
% Create samples for the mass with specified mean and standard deviation.
meanMass = 0.078;
sdMass = 0.0078;
mass = sdMass .* randn(10000,1)+ meanMass;
% Create samples for the diameter with specified mean and standard deviation.
meanDiameter = 2;
sdDiameter = 0.1;
diameters = sdDiameter .* randn(10000,1) + meanDiameter;
% Find the volumes
volumes = (4/3) * pi * (diameters/2) .^ 3;
% Find the density
density = mass ./ volumes;
grid on;
title('Density Distribution', 'FontSize', 15);
xlabel('Density', 'FontSize', 15);
ylabel('Count', 'FontSize', 15);
Image Analyst
Image Analyst on 30 Aug 2016
Edited: Image Analyst on 30 Aug 2016
Other than non-descriptive variable names, the main error was using m slash instead of m dot slash, which will do an element by element divide instead of a matrix inverse.
Also, please read this for your future posts.

Sign in to comment.


Find more on Graphics Object Programming in Help Center and File Exchange


No tags entered yet.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by