I have numbers with upto 10 decimal points stored in a text file.
I read it in MATLAB and then do str2double on the number but i get only upto 4 decimal points. What should I do to get all the values after decimal.
Forexample:
str2double('-122.345464646')
ans =
-122.3455
but I need the entire number
Thanks
Please follow the below steps:
Go to preference
List item
Go to Command Window Option
Then change the numeric format to long g
Alternatively, type long g in command window
Related
I want to run harmoney search algorithm in matlab, and my data set is the number of feature saved in excel with 11 column, I read my file from excel with this command A=xlsread(filename); in matlab, and my file has the value of 0 1 and decimal number, but when I run my program I get NaN instead of decimal number in the out put. so I get NaN value for my best cost, how can I fix this problem?
Let's say I create some number A, of the order 10^4:
A = 81472.368639;
disp(A)
8.1472e+04
That wasn't what I wanted. Where are my decimals? There should be six decimals more. Checking the variable editor shows me this:
Again, I lost my decimals. How do I keep these for further calculations?
Scientific notation, or why you didn't lose any decimals
You didn't lose any decimals, this is just MATLAB's way of displaying large numbers. MATLAB rounds the display of numbers, both in the command window and in the variable editor, to one digit before the dot and four after that, using scientific notation. Scientific notation is the Xe+y notation, where X is some number, and y an integer. This means X times 10 to the power of y, which can be visualised as "shift the dot to the right for y places" (or to the left if y is negative).
Force MATLAB to show you all your decimals
Now that we know what MATLAB does, can we force it to show us our number? Of course, there're several options for that, the easiest is setting a longer format. The most used for displaying long numbers are format long and format longG, whose difference is apparent when we use them:
format long
A
A =
8.1472368639e+04
format longG
A
A =
81472.368639
format long displays all decimals (up to 16 total) using scientific notation, format longG tries to display numbers without scientific notation but with most available decimals, again: as many as there are or up to 16 digits, both before and after the dot, in total.
A more fancy solution is using disp(sprintf()) or fprintf if you want an exact number of decimals before the dot, after the dot, or both:
fprintf('A = %5.3f\n',A) % \n is just to force a line break
A = 81472.369
disp(sprintf('A = %5.2f\n',A))
A = 81472.37
Finally, remember the variable editor? How do we get that to show our variable completely? Simple: click on the cell containing the number:
So, in short: we didn't lose any decimals along the way, MATLAB still stores them internally, it just displays less decimals by default.
Other uses of format
format has another nice property in that you can set format compact, which gets rid of all the additional empty lines which MATLAB normally adds in the command window:
format compact
format long
A
A =
8.147236863931789e+04
format longG
A
A =
81472.3686393179
which in my opinion is very handy when you don't want to make your command window very big, but don't want to scroll a lot either.
format shortG and format longG are useful when your array has very different numbers in them:
b = 10.^(-3:3);
A.*b
ans =
1.0e+07 *
0.0000 0.0001 0.0008 0.0081 0.0815 0.8147 8.1472
format longG
A.*b
ans =
Columns 1 through 3
81.472368639 814.72368639 8147.2368639
Columns 4 through 6
81472.368639 814723.68639 8147236.8639
Column 7
81472368.639
format shortG
A.*b
ans =
81.472 814.72 8147.2 81472 8.1472e+05 8.1472e+06 8.1472e+07
i.e. they work like long and short on single numbers, but chooses the most convenient display format for each of the numbers.
There's a few more exotic options, like shortE, shortEng, hex etc, but those you can find well documented in The MathWork's own documentation on format.
I have a matrix of order 3 x 3, and all elements of matrix are up to 6 decimal place. I want to display this elements of matrix only up to 5 decimal place. I used format short and format long, but it gives either 4 or 15 decimal places.
Is there a command that gives up to any particular decimal places?
I have idea for a single number but could not solve for all entries of a matrix.
The builtin format options cannot handle this. You'll instead want to use fprintf or num2str (with a format specifier) to force the appearance of the number
data = rand(3) * 100;
num2str(data,'%12.5f')
% 20.42155 3.95486 91.50871
% 9.28906 87.24924 72.61826
% 47.43655 95.70325 94.41092
If you want to make this the default display at the command line you could overload the builtin display method for double but I would not recommend that.
Alternately, you can use vpa to specify the number of significant digits to display (note that the second input is the number of significant digits and not the number of numbers after the radix point).
vpa(data, 5)
I need to generate a random number that is between .0000001 and 1, I have been using rand(1) but this only gives me 4 decimal points, is there any other way to do this generation?
Thanks!
From the Octave docs:
By default, Octave displays 5 significant digits in a human readable form (option ‘short’ paired with ‘loose’ format for matrices).
So it's probably an issue with the way you're printing the value rather than the value itself.
That same page shows the other output formats in addition to short, the one you may want to look in to is long, giving 15 significant digits.
And there is also the output_precision which can be set as per here:
old_val = output_precision (7)
disp (whatever)
old_val = output_precision (old_val)
Set the output_precision to 7 and it should be ok :)
Setting the output precision won't help though because the number can still be less than .0000001 in theory but you will only be displaying the first 7 digits. The simplest way is:
req=0;
while (req<.0000001)
req=rand(1);
end
It is possible that this could get you stuck in a loop but it will produce the right number. To display all the decimals you can also use the following command:
format long
This will show you 15 decimal places. To switch back go:
formay short
how to write a lisp program to convert given hexadecimal number into decimal. can somebody give me a clue.
thank you
I'm assuming its a homework problem so i'll give you a hint in the right direction.
Here is how to convert decimal to binary ->
Lets say you start with the number 9 in binary its 1001.
Start of by dividing 9 by 2. You get 4 with remainder 1. Save the remainder.
Now divide that 4 by 2 again, you get 2 with remainder 0. Save the remainder.
Divide that 2 again by 2, you get 1 with remainder 0. Save the remainder.
Divide that 1 by 2 and finally you get 0 with reaminder 1. Save the remainder.
If you read the saved remainders backwards you get 1001! The binary number you've been looking for. Best to push the remainders on the stack and pop them back out, that way they'll come out backwards.
It's already provided by Common Lisp.
The input is the string for the hex integer.
Then you parse the integer with radix 16
the result is the number
if you write the number with base 10 to an output stream, then you can get the number as a string in base 10