From owner-bug-octave at bevo dot che dot wisc dot edu  Thu Dec 19 01:17:01 1996
Subject: Re: fscanf reads strange values on Octave 2.0 /linux
From: Tapani Stipa <stipa at kuohu dot fimr dot fi>
To: "John W. Eaton" <jwe at bevo dot che dot wisc dot edu>
cc: bug-octave at bevo dot che dot wisc dot edu
Date: Thu, 19 Dec 1996 09:13:07 +0200 (EET)

On Wed, 18 Dec 1996, John W. Eaton wrote:

> If you use "%lf", I think you will get the result you expect.

Indeed. Thank you for the hint. There seems to be some contradiction
between this behaviour and the info manuals:

>>

Numeric Input Conversions
-------------------------

   This section describes the `scanf' conversions for reading numeric
values.

   The `%d' conversion matches an optionally signed integer in decimal
radix.

   The `%i' conversion matches an optionally signed integer in any of
the formats that the C language defines for specifying an integer
constant.

   For example, any of the strings `10', `0xa', or `012' could be read
in as integers under the `%i' conversion.  Each of these specifies a
number with decimal value `10'.

   The `%o', `%u', and `%x' conversions match unsigned integers in
octal, decimal, and hexadecimal radices, respectively.

   The `%X' conversion is identical to the `%x' conversion.  They both
permit either uppercase or lowercase letters to be used as digits.

   Unlike the C language `scanf', Octave ignores the `h', `l', and `L'
modifiers.

<<

> However, I'm not sure that Octave should try to follow the semantics
> of C this closely.  Perhaps it would be more useful if "%f" and "%lf"
> were equivalent.  Does anyone have any strong opinions either way?

I would be very much for the option that Octave should read its native
precision with the "%f" format, as some sort of intuition would suggest (I
think Matlab does it this way? cannot test now ... this would of course
not be an excuse by itself ...). 

Just wondering: is there any need to read single precision floats if there
is no internal format for them? 

Best Regards,

Tapani
--
Tapani Stipa, Finnish Institute of Marine Research
PL 33, FI-00931 HELSINKI, Finland
tel. +358-9-613 941 fax +358-9-613 94 494