in reply to Re: How do I make a histogram Question?
in thread How do I make a histogram Question?

Ok, thanks for the help. I was trying to use your code and do a

gsl_histogram_fscanf($stream, $h)

What is the $stream? I read it has been opened by the gsl_fopen_function from the Math::GSL module. Does that mean it is already predefined and I don't have to define it myself. I get a compile error.

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Re^3: How do I make a histogram Question?
by JadeNB (Chaplain) on Jan 28, 2009 at 02:36 UTC
    The simple answer is that you need first to run 
    my $stream = Math::GSL::gsl_fopen $file, $mode;

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    The complicated answer is that gsl_fopen is defined in Math::GSL, which uses the fopen function from Math::GSL::Vector (for some reason), which is an alias of Math::GSL::Vectorc::fopen, whose definition I can't find—so I can't tell you anything but the obvious about $file, and nothing at all about $mode, except that it can end in +b.

    For future reference, it would have been perfectly OK to continue our discussion in the Chatterbox.

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      Thanks for your help JadeNB. Hmm, I added that but I get a unhandled win32 exception. Here is the code that I have. 
      use Math::GSL::Histogram qw/:all/;
use Math::GSL;

$file = "blah.txt";
$mode = 1;

$h = gsl_histogram_alloc(3);
gsl_histogram_set_ranges($h, [0, 41, 61, 100], 4);
gsl_histogram_increment ($h, 0);
gsl_histogram_increment ($h, 41);
gsl_histogram_increment ($h, 61);
gsl_histogram_increment ($h, 100);
$stream = Math::GSL::gsl_fopen $file, $mode;
gsl_histogram_fscanf($stream, $h);

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      How am I doing this wrong?
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        I'm not really up to speed with this, but I think you might want something like: 
        use Math::GSL::Histogram qw/:all/;
use Math::GSL qw/:all/;

$file = "blah.txt";
$mode = 'w';

$h = gsl_histogram_alloc(3);
gsl_histogram_set_ranges($h, [0, 41, 61, 100], 4);
gsl_histogram_increment ($h, 0);
gsl_histogram_increment ($h, 41);
gsl_histogram_increment ($h, 61);
gsl_histogram_increment ($h, 100);
$stream = gsl_fopen $file, $mode;
gsl_histogram_fprintf($stream, $h, '%f', '%f');

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        At least that runs without error. On my Windows Vista box, I need to view 'blah.txt' in something like wordpad. For me, notepad ignores the newlines.

        It might be worth your while to download the Math::GSL source from CPAN, as the test files (in the 't' folder) provide useful examples of correct usage.

        Cheers,
        Rob
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