Christopher2222

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11 years, 362 days

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These are questions asked by Christopher2222

choosing lightmodel=none and shading=none, produces a dark grey grided surface
plot3d(x*y, x = 0 .. 10, y = 0 .. 10, lightmodel = none, shading = none)

adding the style=wireframe option gives a blank plot.  Grid probably white?  Changing style to patchnogrid the surface is indeed white. However chosing both shading and style options to none regardless of the lightmodel will produce a plot that appears empty.  Is this to be expected?

However, just the style=wireframe option produces a colored grided wireframe as to expect
plot3d(x*y, x = 0 .. 10, y = 0 .. 10, lightmodel = none, style = wireframe)

Projection will not work with orientation. 

plot3d(x*y, x = 0 .. 10, y = 0 .. 10, projection = 0.2)
                                                        

plot3d(x*y, x = 0 .. 10, y = 0 .. 10, projection = 0.2, orientation = [55, 75, 0])
                                                

I keep getting errors empty sets or only header information using the HTTP or URL package to when trying to download files from here through Maple. 

How do I download the csv files from here?
https://github.com/CSSEGISandData/COVID-19/tree/master/csse_covid_19_data/csse_covid_19_time_series

 

Noticed an issue with Vector and excel.  Not even really excel but I found it through that.  

If I select a row in excel and do a copy paste into Maple it sometimes appears as if it's a list.  ie it shows up as [1,2,3,4]  other times it shows up as [ 1 2 3 4 ] signifying an array (for this example I've saved as the data under the variable a).  Running whattype(a) on the data shows they're both arrays.  Of course it's probably wise to instead load data through Excel into Maple by using the ExcelTools and Import option, however I didn't think there was no reason to use the copy paste option.  It does, to some extent, or maybe, well, it shows a limitation.

In the first instance when it shows up as a list, I thought it might be simple enough just to add other numbers in the list ie/ just tack on ,5,6,7,8 after the 4.  But after pressing enter we get the error

Error, invalid sequence

I don't understand why I couldn't just add to the copied data but maybe it's the formatting of the data that was pasted into maple? 

With the original copied data, I can use with(plots):  listplot(a) no problem however, we want to add data.  ArrayTools will let us Append data to the vector

with(plots):
with(ArrayTools):
Append(a,5,6,7,8)

listplot(a) # will throw another error

                  Error, (in plots:-pointplot) points cannot be converted to floating-point values (this doesn't show in Maple 2019 but does come up in Maple 18)

For Maple 2019 it with responds with a returned array [ 1 2 3 4 5,6,7,8]

Running listplot on that Appended Array.  Maple only recognizes the next 1 added value.

So this means appending values using ArrayTools and Append only allows us to append one value at a time?  Is that a bug?  Are there better ways to append values to vectors?  The only solution for that is to convert to a list and use op to append more values.  But perhaps Maple should have understood the copied values from Excel should have been a list or listlist of values?

 

 

 

Since maple doesn't have mp3 support, the best we can do is just convert to a supported file type and go from there.  We can actually use maple's system command to work within maple to accomplish this and other tasks.  Actually someone using Matlab created an FFmpeg tool package - something similar could also be done with Maple.

So first you need to load the free open source FFmpeg software into your machine.  I'm using windows so Unzip into a folder then into right click on mycomputer go into properties advanced and add a new environment variable.

However I'm having a problem using the ssystem command.  The system command actually works fine, so I don't know if it's an issue with my format of the command or maybe it's a bug within the Maple 18 that I'm currently working in (perhaps it works on the newer versions) so here's the script

system("ffmpeg -i c:/test/test.mp3") #works fine outputed in a new window displays info about specified file

ssystem("ffmpeg -i c:/test/test.mp3") #maple is busy sitting executing with nothing happening

However this works,

ssystem("ffmpeg -version") #does output into Maple just information of the ffmpeg software version

so I suspect something to do with the file formatting??  Any ideas why ssystem doesn't output into maple using a file location?

 

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