Sig figs on the rand function

Just another general question here, is there a reason the rand function has 6 sig figs? i.e. 12.3456

Is there a way to change this so there are more or less post decimal? Or is this just how MATLAB handles this function, generally.

Thank you in advance!

Answer 1

[Chunru]

==> Just another general question here, is there a reason the rand function has 6 sig figs? i.e. 12.3456

rand function (by defaut) has "double" type, which means it is represented internally by 64bits, precision of up to 15 digits.

MATLAB has a default display format, which is "short" and has 4 digits after decimal point (Note: this is only for display, internal computations are based on double).

==>Is there a way to change this so there are more or less post decimal? Or is this just how MATLAB handles this function, generally.

Use format long to display data with more digits after decimal point (doc format for more details)

a = rand();         % internally stored as double
a                   % default (4 digits after dp)

a = 0.0083

format long         % (15 digits after dp)
a

a = 
   0.008251124809451

[Spaceman]

Thank you! The world of computing and coding is so interesting. I will be using the format long function in the future for curiosity sake alone! In my example, where would I put 'format long' in my code to show all 15 digits?

% format long?
grade=rand(1,49)*(100-20)+20; % could also do randi([20 100],1,49);
% format long?
grade_avg=mean(grade);
fprintf('The average grade is %1.0f \n',grade_avg)
if grade_avg>=60
    disp('passing average')
else
    disp('failing average')
end

Also how would I revert back to the standard format? 'format short'?

[Chunru]

% format long?
format long
grade=rand(1,49)*(100-20)+20; % could also do randi([20 100],1,49);
% format long?
grade_avg=mean(grade);
grade_avg

grade_avg = 
  61.084787400165922

% Use fprintf for more control of the format
%fprintf('The average grade is %1.0f \n',grade_avg)
fprintf('The average grade is %0.10f \n',grade_avg)  % 10 digits after dp

The average grade is 61.0847874002 

if grade_avg>=60
    disp('passing average')
else
    disp('failing average')
end

passing average

format default      % revert to default
grade_avg

grade_avg = 61.0848

[Spaceman]

Thank you. So default format is 'format short'. The power MATLAB holds is but only scratched on the surface by me.