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Sig figs on the rand function

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Spaceman
Spaceman on 20 Mar 2024
Commented: Spaceman on 20 Mar 2024
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!

Accepted Answer

Chunru
Chunru on 20 Mar 2024
==> 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
  3 Comments
Chunru
Chunru on 20 Mar 2024
% 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
Spaceman on 20 Mar 2024
Thank you. So default format is 'format short'. The power MATLAB holds is but only scratched on the surface by me.

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