request by teacher Wed 1/4/2012 3:47 PM

We are wondering if you could include an optional check box to show
(i) the displacement-time graphs of S1, S2 and the resultant at any position
[color=blue][b]added [/b][/color]
(ii) the intensity-position profile of the resultant wave
[color=red]working on it, maybe next week can produce [/color]
As we explore the EJS, we realize that after some time, it seems that the resultant pattern was not correctly represented. We wonder if there might be a bug there. I have attached a word document for your reference.
[color=blue][b]i fixed the bug by moving the codes to evolution page instead of fixed relationship, was difficult to find the bug or cause, but i did it! :)[/b][/color]

Also, we found that there may be no need to move the source horizontally, thus would it be possible to remove the slider-bars so as to keep the platform neater.
[b][color=blue]made hide and show after clicking the check-boxes, a bit neater now, we agree that it could be still useful to be able to fine-control position of S1 and S2, let keep it inside the sim :)[/color][/b]

request by teacher Thu 1/5/2012 9:34 AM
I just managed to run the superposition EJS and would like to request the following changes if possible:

1. Currently in the graph mode, the pattern shifts right to the top and it is difficult to identify the position of P. I wonder if the graphs could be shown individually on the right side of the panel so that the students know which graph corresponds to which source and know which is the resultant wave. I would propose that the size of the pattern should remain the same, if possible.
[color=blue][b]i added a margin 10%, now can see the maximum and minimum values of 2 and -2 easily. [/b][/color]


2. Currently, after running the EJS in the graphical mode and pausing it to show the step function. The graph continues to show the same shape. Clicking the step button causes the graph to shift forward in time, I was a bit confused initially trying to interpret the implication of the graph. I wonder if there is any way to help clarify this by looking at the graph. If not, I suppose the worksheet will need to try explain the meaning of it.

[color=blue][b]the graph data was currently is set to display only 75 data-points, to save memory.
if i set to infinity, it will slow down as the calculation to display all the infinity point takes a lot of memory.[/b][/color]



3. After pausing the EJS, I start to shift point P around. Initially the graph still looks sinusoidal but after some time, the graph shows vertical line corresponds to the particular time paused. As the lines all overlap, I could not figure out what they are the values of the lines. The line does not seem to correspond correctly to the pattern as I shift point P around.

[color=blue][b]the student-scientist need to understand the graph shows old data, to collect new data on new position of P, click play again to start collect y1+y2 at P.
the values can be read from the bars on the right. :)[/b][/color]

Thanks for the great simulation!
[color=blue][b]my pleasure :)[/b][/color]


On a side note, for those who downloaded the file *.jar, Windows7 may associate it as a zip file. What my TA did was to change the file extension to jar instead of zip. To view the file extension, you would need to go the folder option/view and unchecked the "hide file extension".
[b][color=blue]yes agreed.[/color][/b]


SMS Thu 1/5/2012 12:16 PM
Hi, my colleague prefers to view the JS without colors. Can this be the default screen? Also it seems that the legend slows down the system a bit. We think there may be no need for the legend, if it affects the computation. Ty.
[color=blue][b]done[/b][/color]

SMS Thu 1/5/2012 12:26 PM
Thanks. Btw, did you experience the program hanging after some time, especially after changing the phase a few times and allowing it to run say around 100 s  the EJS starts to slow down till it has no response
[color=blue][b]i didn't notice it on my computer, i ran for >100 seconds.[/b][/color]

fix a useability issue of S12 and S2 draggable on simulation is playing, change to only when paused.

fix an array issue of border top and right white by  changing sum = [number][number]