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Date: Fri, 10 Jun 2016 17:11:49 -0700 (PDT)
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Subject: BUG: binary data is not being interpreted correctly
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Xref: csiph.com comp.graphics.apps.gnuplot:3339

I create a small binary file and it is ok, but when the binary file gets to a certain size, it goes all wonky.  Here is a C++ binary file generator:

#include <limits>
#include <iostream>
#include <assert.h>

template <typename T1, typename T2>
void write(std::ostream& os, T1 x, T2 y)
{
	using namespace std;
	static int counter = 0;
	assert(0 <= x);
	assert(0 <= y);
	assert(x < numeric_limits<double>::max());
	assert(y < numeric_limits<double>::max());
	double array[2] = { (double)x, (double)y };
	os.write((char*)array, sizeof(array));
	os.flush();
	++counter;
}

int main()
{
	using namespace std;
	ofstream os;
	os.open("data.dat");
	uint64_t y_value = 0;
	for (uint64_t x_value = 0; x_value < 5000; ++x_value)
	{
		write(os, x_value, y_value);
		if (x_value % 10 == 0)
		{
			++y_value;
		}
	}
	return 0;
}

It just creates a stepping function, increasing 1 every 10.  I then read the file using the command:

plot 'data.dat' binary format='%lf%lf' 0:1

If I read the file before it gets too big, I get an increasing stepping function.  If I get to around 2000, I get some negative values.