Re: [Visualpython-users] Re:How to print ?

[Bruce S. <ba...@an...>]

I installed DISLIN, tried a simple demo, and looked at the documentation. 
DISLIN is an excellent graphing package to go with Python, but as far as I 
can tell it does not address the graphing needs of my physics students. 
(And I don't see how to get a Mac version created.)

The input to DISLIN plotting routines are arrays of data. We don't even 
teach our students about arrays! A typical student program computes step by 
step the motion of (say) a binary star, with a display of the two stars in 
motion. Often there is an accompanying graph of (say) energy vs. time, with 
data points added one at a time to the graph as they are computed. Both the 
motion of the stars and the graph evolve in time, with continual updates.

The reason why we are able to introduce serious computer modeling with 3D 
animations into an introductory physics course is that we can spend just 50 
minutes teaching a very small subset of Python, adequate for modeling a 
range of physical systems, even if the student has never written a program 
before. In this minimalist situation, arrays are one of the very many 
features of Python which we don't introduce. Moreover, we want the graph 
and the animation to run continuously, in parallel. If the issue were 
simply that of making graphs, in the absence of DISLIN we could just have 
students write data to a data file and import that file into Excel or other 
graphing package.

Being able to graph incrementally is a bit tricky, because for autoscaling 
you need incrementally to detect the need to change the axes, tick marks, 
and labels, and rearrange the screen. That's what visual.graph does (and 
dislin doesn't, because it plots arrays, not individual points). So I say 
again that it would be useful to have the ability for visual.graph to 
output postscript and print, even with the availability of the excellent 
DISLIN library.

Bruce Sherwood