Groups > comp.lang.java.programmer > #8572

Re: DataInputStream

Date	2011-10-05 08:38 -0700
From	Patricia Shanahan <pats@acm.org>
Newsgroups	comp.lang.java.programmer
Subject	Re: DataInputStream
References	<1418dd7f-d5d1-4a2c-b77b-87666f6a9591@k15g2000yqd.googlegroups.com> <9f2a8cFh1nU1@mid.individual.net> <6cf66421-77a9-4088-b810-3bcc958cc8ca@i28g2000yqn.googlegroups.com> <2ec7550a-a3d9-40a9-bca1-e1fd2586429d@g33g2000yqc.googlegroups.com> <02b9b80f-ff02-499d-8f33-056080b114bb@s9g2000yql.googlegroups.com>
Message-ID	<lbadnQCmK7CB5xHTnZ2dnUVZ_qydnZ2d@earthlink.com> (permalink)

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On 10/5/2011 7:17 AM, bob wrote:
> The issue is that it's too slow.
>
> What I'm hoping for is something like this:
>
> 			byte[] b = new byte[numfloats*4];
> 			dis.read(b, 0, numfloats*4);
> 			float[] f = (float[]) b;
> 			return f;
>
> I don't know why, but it won't let me do the cast.  Any ideas?

Perhaps because you used a Java compiler, rather than a C compiler.

In Java, there are no guarantees about how arrays are arranged in
memory, so a cast from byte[] to float[] would not have defined results.

If it remains too slow even with buffering, you may need to consider
alternative such as matlab, Fortran, or C. Java tends not to be the
fastest language for bulk operations on floating point data.

Patricia

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Thread

DataInputStream bob <bob@coolgroups.com> - 2011-10-04 22:34 -0700
  Re: DataInputStream Robert Klemme <shortcutter@googlemail.com> - 2011-10-05 08:02 +0200
    Re: DataInputStream bob <bob@coolgroups.com> - 2011-10-04 23:17 -0700
      Re: DataInputStream Robert Klemme <shortcutter@googlemail.com> - 2011-10-05 00:07 -0700
        Re: DataInputStream bob <bob@coolgroups.com> - 2011-10-05 07:17 -0700
          Re: DataInputStream markspace <-@.> - 2011-10-05 08:27 -0700
          Re: DataInputStream Patricia Shanahan <pats@acm.org> - 2011-10-05 08:38 -0700
          Re: DataInputStream Robert Klemme <shortcutter@googlemail.com> - 2011-10-05 08:58 -0700
            Re: DataInputStream Lew <lewbloch@gmail.com> - 2011-10-05 14:52 -0700
              Re: DataInputStream Patricia Shanahan <pats@acm.org> - 2011-10-05 15:15 -0700
              Re: DataInputStream Robert Klemme <shortcutter@googlemail.com> - 2011-10-06 00:11 -0700
                Re: DataInputStream Lew <lewbloch@gmail.com> - 2011-10-06 07:08 -0700
                Re: DataInputStream Patricia Shanahan <pats@acm.org> - 2011-10-06 07:49 -0700
          Re: DataInputStream Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-10-05 21:16 -0400
      Re: DataInputStream Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-10-05 08:12 +0000
        Re: DataInputStream bob <bob@coolgroups.com> - 2011-10-05 07:12 -0700
  Re: DataInputStream Roedy Green <see_website@mindprod.com.invalid> - 2011-10-06 02:48 -0700

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