Re: plot matrix?

[Daniel J S. <dan...@ie...>]

Hi Philipp,

The interpretation of matrix can vary depending on the item being plotted.

First, "matrix" by itself is a legacy keyword that is still accepted for backward compatibility.  It's gnuplot's matrix format, who's definition is given in the documentation.

Images are the plot elements that makes sense in a matrix format for "plot".  Color can be five dimensional, alpha-channel six dimensional.

You asked about the legality of some syntax.  The answer is maybe yes, maybe no.  It depends on whether it makes sense for the elements being plotted.  In some circumstances there are default column definitions.  It's still open for discussion.

Dan



Philipp K. Janert wrote:
> I am not sure how the "matrix" keyword works
> (that is: is supposed to work) when used together
> with the plot (not splot) command.
> 
> Can you help me to enumerate the legal uses?
> 
> For splot, there seem to be two legal ways to use
> matrix:
> 
> 	splot "file" matrix 
> and
> 	splot "file" matrix u ($1):($2):3
> 
> The first assumes the values in the file to be z-values
> on a regular grid.
> 
> The second assumes that the z-values are in "column"
> 3, and allows me to fix the x- and y-coordinates through
> the "columns" 1 and 2.
> 
> Is it legal to do either:
> 
> 	splot "file" matrix u 1
> or
> 	splot "file" matrix 1:2
> 
> And if so, what do either of them do?
> 
> For plot (not splot), I am completely confused. Does
> it even make sense to have the notion of a "matrix"
> format for plot? The "matrix" keyword seems to suggest
> that the data is on a regular, 2-dim grid. This notion 
> does not seem to have any meaning for plot.
> 
> Best,
> 
> 		Ph.
> 
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Dan Sebald
email: daniel(DOT)sebald(AT)ieee(DOT)org
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