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Summary
Licensing
I, the copyright holder of this work, hereby publish it under the following licenses:

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no FrontCover Texts, and no BackCover Texts. A copy of the license is included in the section entitled GNU Free Documentation License. http://www.gnu.org/copyleft/fdl.htmlGFDLGNU Free Documentation Licensetruetrue

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Source
This image has been created using python and can also be plotted using the following matlab source code.
margin = 0.3;
x = 0:0.01*pi:8*pi; y = sinint(x);
plot(x,y); hold on
plot( [min(x) max(x)], [pi/2 pi/2] , 'k:') % the asymptote
axis([min(x) max(x) min(y) max(y)+margin])
title('{\bfSine integral}'); legend('Si({\itx})', 'asymptote at {\itx}\rightarrow\infty')
xlabel('$x$', 'Interpreter','latex')
ylabel('${\mathop{\rm Si}\nolimits} \left( x \right) = \int\limits_0^x {\frac{{\sin t}}{t}dt}$',...
'Interpreter','latex')
File usage
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