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Printing a floating point number

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  Printing a floating point number jsgraham <jsgrahamus@yahoo.com> - 2011-04-27 13:09 -0600
    Re: Printing a floating point number mhx@iae.nl (Marcel Hendrix) - 2011-04-27 22:03 +0200
    Re: Printing a floating point number stephenXXX@mpeforth.com (Stephen Pelc) - 2011-04-27 20:52 +0000
      Re: Printing a floating point number jsgraham <jsgrahamus@yahoo.com> - 2011-04-27 15:47 -0600
      Re: Printing a floating point number jsgraham <jsgrahamus@yahoo.com> - 2011-04-28 00:49 -0600
        Re: Printing a floating point number stephenXXX@mpeforth.com (Stephen Pelc) - 2011-04-28 09:13 +0000
          Re: Printing a floating point number mhx@iae.nl (Marcel Hendrix) - 2011-04-28 21:08 +0200

#1580 — Printing a floating point number

How does one do this in Forth?  I have VFX Forth and I pushed 3.14 onto 
the stack and tried executing F., for which I got an UNDEFINED WORD error.

I know I'm missing something simple here.


Steve

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#1583

jsgraham <jsgrahamus@yahoo.com> writes Re: Printing a floating point number

> How does one do this in Forth?  I have VFX Forth and I pushed 3.14 onto 
> the stack and tried executing F., for which I got an UNDEFINED WORD error.

> I know I'm missing something simple here.

Interlocking problems are always difficult.

The solution for your first problem is:  3.14e0 ( 3.14 is a double
number and the '.' does not mean what you think it means, that's why
modern Forth advises to always write 314. )

Because of the second problem, you will get an error even if you 
guessed '3.14e' needs to be written.

The solution to the second problem is loading the Floating-point 
package *before* trying to use any of its words (here F. and FP 
number evaluation). (VFX is not alone in failing to include FP in
the default startup, SwiftForth has the same annoying behavior.) 
The VFX manual has ample documentation on how to do this -- although 
I still not succeeded in creating a .ini file to handle it 
automatically for me.

-marcel

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#1590

On Wed, 27 Apr 2011 13:09:24 -0600, jsgraham <jsgrahamus@yahoo.com>
wrote:

>How does one do this in Forth?  I have VFX Forth and I pushed 3.14 onto 
>the stack and tried executing F., for which I got an UNDEFINED WORD error.
>
>I know I'm missing something simple here.

There are three floating point packs for VFX Forth, so you have to
select which one to use. In nearly all cases, Lib\Ndp387.fth is the
best choice. Assuming that the LIB macro is set up:

  include %lib%\Ndp387
  3.14e0 f.

In order to prevent parsing issues, specifying an exponent is good
practice.

Stephen

-- 
Stephen Pelc, stephenXXX@mpeforth.com
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeforth.com - free VFX Forth downloads

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#1592

Stephen Pelc wrote:
> On Wed, 27 Apr 2011 13:09:24 -0600, jsgraham<jsgrahamus@yahoo.com>
> wrote:
>
>> How does one do this in Forth?  I have VFX Forth and I pushed 3.14 onto
>> the stack and tried executing F., for which I got an UNDEFINED WORD error.
>>
>> I know I'm missing something simple here.
>
> There are three floating point packs for VFX Forth, so you have to
> select which one to use. In nearly all cases, Lib\Ndp387.fth is the
> best choice. Assuming that the LIB macro is set up:
>
>    include %lib%\Ndp387
>    3.14e0 f.
>
> In order to prevent parsing issues, specifying an exponent is good
> practice.
>
> Stephen
>

Thanks, Stephen

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#1610

Stephen Pelc wrote:
> On Wed, 27 Apr 2011 13:09:24 -0600, jsgraham<jsgrahamus@yahoo.com>
> wrote:
>
>> How does one do this in Forth?  I have VFX Forth and I pushed 3.14 onto
>> the stack and tried executing F., for which I got an UNDEFINED WORD error.
>>
>> I know I'm missing something simple here.
>
> There are three floating point packs for VFX Forth, so you have to
> select which one to use. In nearly all cases, Lib\Ndp387.fth is the
> best choice. Assuming that the LIB macro is set up:
>
>    include %lib%\Ndp387
>    3.14e0 f.
>
> In order to prevent parsing issues, specifying an exponent is good
> practice.
>
> Stephen
>

Is there a way to print a float in a base other 10?


Steve

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#1613

On Thu, 28 Apr 2011 00:49:44 -0600, jsgraham <jsgrahamus@yahoo.com>
wrote:

>Is there a way to print a float in a base other 10?

No.

Stephen

-- 
Stephen Pelc, stephenXXX@mpeforth.com
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeforth.com - free VFX Forth downloads

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#1629

stephenXXX@mpeforth.com (Stephen Pelc) writes Re: Printing a floating point number

> On Thu, 28 Apr 2011 00:49:44 -0600, jsgraham <jsgrahamus@yahoo.com> wrote:

>>Is there a way to print a float in a base other 10?

> No.

FORTH> needs hexfloat
Creating --- Hexfloat            Version 2.01 ---

Convert among IEEE 754 32-bit, 64-bit or 80-bit float,
C99 mixed hex/decimal string, and raw hex string formats.
User words:
   xf>hex$ df>hex$ sf>hex$ -- ( F: r -- ) ( -- c-addr u )
   hex$>xf hex$>df hex$>sf -- ( c-addr u -- ) ( F: -- r )
   xf>mix$ df>mix$ sf>mix$ -- ( F: r -- ) ( -- c-addr u )
   mix$>xf mix$>df mix$>sf -- ( c-addr u -- ) ( F: -- r )

Remark:  The number of digit groups for hex$ is fixed -- groups
         shall have 4 hex digits. Overflow is possible: more
         than 8, 16, or 20 digits for sf, df, xf respectively.
Remark:  For mix$, sign and integer bit are optional, but `.'
         and `p' are mandatory. Contrary to hex$ the number
         of groups is free, but the total number of digits
         of the mantissa should fit in the target float.
 ok
FORTH> pi xf>hex$ TYPE 4000 C90F DAA2 2168 C235  ok
FORTH> pi xf>mix$ TYPE +1.921F B544 42D1 846A p+1 ok
FORTH> 3.14e0 xf>mix$ TYPE +1.91EB 851E B851 EB84 p+1 ok
FORTH> s" +1.91EB 851E B851 EB84 p+1" mix$>xf f. 3.140000  ok

Nothing is impossible in Forth.

-marcel

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