If I set a variable in Matlab, say var1 = 2.111, after running the script, Matlab returns var1 = 2.1110. I want Matlab to return the original number, with no trailing zero. Anyone know how to do this. Thanks in advance.
By default Matlab displays results in Short fixed decimal format, with 4 digits after the decimal point.
You can change that to various other format such as:
long
Long fixed decimal format, with 15 digits after the decimal point for double values, and 7 digits after the decimal point for single values.
3.141592653589793
shortE
Short scientific notation, with 4 digits after the decimal point.
Integer-valued floating-point numbers with a maximum of 9 digits do not display in scientific notation.
3.1416e+00
longE
Long scientific notation, with 15 digits after the decimal point for double values, and 7 digits after the decimal point for single values.
Integer-valued floating-point numbers with a maximum of 9 digits do not display in scientific notation.
3.141592653589793e+00
shortG
The more compact of short fixed decimal or scientific notation, with 5 digits.
3.1416
longG
The more compact of long fixed decimal or scientific notation, with 15 digits for double values, and 7 digits for single values.
3.14159265358979
shortEng
Short engineering notation, with 4 digits after the decimal point, and an exponent that is a multiple of 3.
3.1416e+000
longEng
Long engineering notation, with 15 significant digits, and an exponent that is a multiple of 3.
3.14159265358979e+000
However I don't think other options are available. If you absolutely want to remove those zeros you would have to cast you result in a string and remove the trailing 0 characters and then display your result as a string and not a number.
Related
printf: is it possible to configure the default number of digits used by the exponent.
For portability reason I would like to set the number of digits used for exponents for exponents below 100.
On my machine the default is 2 digits
printf "%.3e\n", 342.7234;
# 3.427e+02
but in How can I convert between scientific and decimal notation in Perl? the exponent has 3 digits.
Quoting from: https://www.mathworks.com/help/symbolic/increase-precision-of-numeric-calculations.html
By default, MATLAB® uses 16 digits of precision.
But why when I write 900000000+2 (8 zeros after 9) it returns 900000002 but writing 900000000+2 (9 zeros after 9)returns 9.0000e+09
isn't this an 8 digit precision?
you use the format command to control how many digits to be printed. help formatto see more details. Try format long g and rerun your command to see more digits.
By default, MATLAB® uses 16 digits of precision.
this refers to computation precision, not the printing precision. By default, MATLAB defines variables as double, which usually is accurate up to 16 digits. But you can print such double precision number in lower previsions (controlled by the format command)
I'm using postgres sql I need 12 digits and after decimal I need only 6 digits what length & Precision should I give in columns.what datatype shold I give to cloumn.
I tried numeric as a datatype and length I give to column is 12 and precision is 6.
If you need 12 digits before the decimal and 6 digits after, you need numeric(18,6)
Quote from the manual
The scale of a numeric is the count of decimal digits in the fractional part, to the right of the decimal point. The precision of a numeric is the total count of significant digits in the whole number, that is, the number of digits to both sides of the decimal point
(Emphasis mine)
So the first number (precision) in the type definition is the total number of digits. The second one is the number of decimal digits.
If you specify numeric(12,6) you have a total of 12 digits and 6 decimal digits, which leaves you only 6 digits for the digits to the left of the decimal. Therefor you need numeric(18,6)
I want to convert a floating point number to string.
f=0.0000
str=num2str(f,4);
This give me this-
str=
0
But I wanted to keep the result till 4 decimal points.I understand using num2str(f,4) results in precision of maximum 4 significant digits after decimal.It is not equal to 4 but maximum and that is why I get this answer.I want to know is there any way to convert this number to string with exactly 4 significant digits after decimal point?
Try using sprintf instead:
str = sprintf('%.4f', f)
I'm aware that double is the default data-type in MATLAB.
When you compare two double numbers that have no floating part, MATLAB is accurate upto the 17th digit place in my testing.
a=12345678901234567 ; b=12345678901234567; isequal(a,b) --> TRUE
a=123456789012345671; b=123456789012345672; isequal(a,b) --> printed as TRUE
I have found a conservative estimate to be use numbers (non-floating) upto only 13th digit as other functions can become unreliable after it (such as ismember, or the MEX functions ismembc etc).
Is there a similar cutoff for floating values? E.g., if I use shares-outstanding for a company which can be very very large with decimal places, when do I start losing decimal accuracy?
a = 1234567.89012345678 ; b = 1234567.89012345679 ; isequal(a,b) --> printed as TRUE
a = 123456789012345.678 ; b = 123456789012345.677 ; isequal(a,b) --> printed as TRUE
isequal may not be right tool to use for comparing such numbers. I'm more concerned about up to how many places should I trust my decimal values once the integer part of a number starts growing?
It's usually not a good idea to test the equality of floating-point numbers. The behavior of binary floating-point numbers can differ drastically from what you may expect from base-10 decimals. Consider the example:
>> isequal(0.1, 0.3/3)
ans =
0
Ultimately, you have 53 bits of precision. This means that integers can be represented exactly (with no loss in accuracy) up to the number 253 (which is a little over 9 x 1015). After that, well:
>> (2^53 + 1) - 2^53
ans =
0
>> 2^53 + (1 - 2^53)
ans =
1
For non-integers, you are almost never going to be representing them exactly, even for simple-looking decimals such as 0.1 (as shown in that first example). However, it still guarantees you at least 15 significant figures of precision.
This means that if you take any number and round it to the nearest number representable as a double-precision floating point, then this new number will match your original number at least up to the first 15 digits (regardless of where these digits are with respect to the decimal point).
You might want to use variable precision arithmetics (VPA) in matlab. It computes expressions exactly up to a given digit count, which may be quite large. See here.
Check out the MATLAB function flintmax which tells you the maximum consecutive integers that can be stored in either double or single precision. From that page:
flintmax returns the largest consecutive integer in IEEE® double
precision, which is 2^53. Above this value, double-precision format
does not have integer precision, and not all integers can be
represented exactly.