Rounding off double precision

On Mar 31, 1:55 pm, Dave Seaman <dsea...@no.such.host> wrote:
> On Mon, 31 Mar 2008 08:15:21 -0700 (PDT), Chip Coldwell wrote: 
> 
> 
>
> Ok, it creates an absolutely useless literal constant with a double
> precision value that can't be referenced anywhere.  Is that better?

The whole point of my post was that there are two ways to go wrong in
one of these parameter statements. You can assign a double precision
literal constant to a single precision named parameter:

REAL PI
PARAMETER(PI=3.141592653589793238d0)

Or, you can assign a single precision literal constant to a double
precision named parameter:

DOUBLE PRECISION PI
PARAMETER(PI=3.141592653589793238)

The result in either case is a single precision *value* stored in
either a single- or double-precision named parameter.

So I think the distinction between a literal constant and a named
parameter is relevant to the discussion.

Chip

>  A parameter is not a literal constant and vice-versa.

what's the difference? I thought parameter was fortran's way of
declaring a constant.

On Mon, 31 Mar 2008 19:43:46 -0700 (PDT), Bamm wrote: 

> what's the difference? I thought parameter was fortran's way of
> declaring a constant.

A parameter is a symbolic constant, not a literal constant.


--
Dave Seaman
Court affirms Judge Yohn's ruling.
<http://www.ipsnews.net/news.asp?idnews=41761>

"Dave Seaman" <dseaman@no.such.host> wrote in message
news:fssah4$iv8$2@mailhub227.itcs.purdue.edu...
> On Mon, 31 Mar 2008 19:43:46 -0700 (PDT), Bamm wrote: 
> 
>
> A parameter is a symbolic constant, not a literal constant.
I think illustrative source snippets go a long way:
INTEGER, PARAMETER :: dp = kind(1d0)
is probably the parameter I get the most mileage from.
--

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Organization: School of Math and Comp Sci, Victoria Uni. of Wellington, New 
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In article <6d59066b-e3dd-4e10-9e1e-f98ce2ca0224@e23g2000prf.googlegroups.co
m>,
Bamm  <bammster@gmail.com> wrote: 
>
>what's the difference? I thought parameter was fortran's way of
>declaring a constant.

Nearly right. It's Fortran's way of declaring a named constant. Constants
are of two kinds: named and literal constants. In the statement
INTEGER, PARAMETER :: two = 2
two is a named constant, and 2 is a literal constant. The difference
sometimes matters, e.g. the next statement may be
CHARACTER stuff*2
but it must not be CHARACTER stuff*two though it may be
CHARACTER stuff*(two)

-- John Harper, School of Mathematics, Statistics and Computer Science,
Victoria University, PO Box 600, Wellington 6140, New Zealand
e-mail john.harper@vuw.ac.nz phone (+64)(4)463 6780 fax (+64)(4)463 5045

"Dave Seaman" <dseaman@no.such.host> wrote in message
news:fsr8r6$uu8$3@mailhub227.itcs.purdue.edu...
> On Mon, 31 Mar 2008 17:45:41 +0100, Les wrote:
>
> 
> 
> 
>
> That, of course, is the preferred Fortran 90 syntax, but the Fortran 77
> method
>
> double precision pi
> parameter (pi = 3.14159265358979d0)
>
> also has the desired effect and is closer to what was originally asked.
>

Oops. Yes of course.
Les

>
>
>
> --
> Dave Seaman
> Court affirms Judge Yohn's ruling.
> <http://www.ipsnews.net/news.asp?idnews=41761>

On Mon, 31 Mar 2008 22:04:56 -0700, Gerry Ford wrote:



> "Dave Seaman" <dseaman@no.such.host> wrote in message
> news:fssah4$iv8$2@mailhub227.itcs.purdue.edu... 
> I think illustrative source snippets go a long way:
> INTEGER, PARAMETER :: dp = kind(1d0)
> is probably the parameter I get the most mileage from.

And in your example, "dp" is a symbolic constant and "1d0" is a literal
constant.


--
Dave Seaman
Court affirms Judge Yohn's ruling.
<http://www.ipsnews.net/news.asp?idnews=41761>

"Dave Seaman" <dseaman@no.such.host> wrote in message
news:fstcm0$4eh$1@mailhub227.itcs.purdue.edu...
> On Mon, 31 Mar 2008 22:04:56 -0700, Gerry Ford wrote:
>
>
> 
>
> And in your example, "dp" is a symbolic constant and "1d0" is a literal
> constant.
I didn't know that.

INTEGER, PARAMETER :: qp = kind(???)

Is there an analogous literal here?  It sounds like I'm trying to buy
pot.:-)

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