Unfamiliar .D0 number syntax

I've inherited some Matlab code that was previously adapted from Fortran, and the Matlab code has a syntax I'm not familiar with. Numbers end with .D0, so I see a lot of lines like:

a = b*5.D0; 

which produces the same result as

a = b*5; 

I haven't found any documentation for this syntax, but it's easy to deduce what it's doing:

>> 12345.D0
ans =
12345
>> 12345.D2
ans =
1234500
>> 12345.D-3
ans =
12.3450

My questions are:

1. What is this syntax called?
2. Is there any particular reason to use it?
3. Can I safely delete every instance of .D0 from this code I've inherited?

Answer 1

[Steven Lord]

This is E notation. I believe MATLAB supports D as well as E because Cleve was inspired by Fortran, which as a comment on that page states "FORTRAN (at least since FORTRAN IV as of 1961) also uses "D" to signify double precision numbers in scientific notation."

x = 3.4e2

x = 340

y = 3.4d2

y = 340

The .D0 indicates that whatever value you're defining is an integer. All of z, w, and q are the same value (five.)

z = 5.0D0

z = 5

w = 5.D0

w = 5

q = 5D0

q = 5

[Chad Greene]

@Steven Lord Thanks, so I guess I can delete the .D0 instances from the code I inherited.

[James Tursa]

@Chad Greene FYI, there is a difference between MATLAB and Fortran for the E notation. In MATLAB the E notation is a double variable same as D notation, but in Fortran the E notation is single precision, not double precision.