Question

Does anyone know a library which generates enthalpy–entropy charts (h-s chart, Mollier h,x Diagramm in german)?

Answer 1

There’s always the gnuplot extension for PHP. I’ve never plotted an enthalpy-entropy chart with gnuplot, but I’m sure it’s perfectly capable.

http://php-gnuplot.sourceforge.net/

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Perhaps a better option is to not use the extension, and run gnuplot directly from a shell script instead. This way you have access to every feature of gnuplot, and aren’t constrained by what the extension does/doesn’t provide.

Here’s a pretty good guide on running gnuplot from a shell script:

http://t16web.lanl.gov/Kawano/gnuplot/intro/working-e.html

And if you need a little primer on gnuplot, there is:

http://www.ibm.com/developerworks/library/l-gnuplot/

Once you have the script, it can be called via exec() in PHP. Don’t forget to chmod +x gnuplot-script.sh first to make it executable.

exec('/path/to/gnuplot-script.sh');