Question

I want a variable in matlab to store(not to be confused with display) only upto 4 decimal places.
Is there an inbuilt command for it?
I tried the following – but this gives an error:

a = [5.21365458 5.236985475 1.236598547 9.3265874];

k=1;
for i=1:length(a)
ast(k)=sprintf('%5.4f',a(i));
anum(k)=str2num(ast(k));
k=k+1;
end

error is : ??? Subscripted assignment dimension mismatch.

Answer 1

You should round the numbers to four decimal places. This is easy to do in the workspace:

>> x = rand(1,4)
x =
   0.053378064308120   0.051670599653141   0.924623792776560   0.585692341974519
>> x = round(x*1e4) / 1e4
x =
   0.053400000000000   0.051700000000000   0.924600000000000   0.585700000000000

or you could write a function roundToDP(x,numberOfDecimalPlaces) that does it for you:

function x = roundToDP(x,n)
% "Round the matrix x to n decimal places"
x = round(x * 10^n) / 10^n;

now you can use that function in the workspace:

>> x = rand(1,4)
x =
   0.810201981892601   0.165116049955136   0.457688639337064   0.985975706057179
>> roundToDP(x,4)
ans =
   0.810200000000000   0.165100000000000   0.457700000000000   0.986000000000000