plot3d takes "forever" to plot x^2*y

[jwmerrill]

sage: var('y')
sage: plot3d(x^2*y,(-1,1),(-1,1))

This takes for ever, even when run as the first command after restarting a notebook. On the other hand, it takes about 1 second to do

sage: var('y')
sage: plot3d(sin(sin(x) + y^2),(-1,1),(-1,1))

[mhansen]

What version of Sage are you running?

[jwmerrill]

3.1.2.alpha2

[mabshoff]

Yep, this computation still calls Maxima. Any idea why _fast_float is not used?

Cheers,

Michael

[mhansen]

I can't duplicate this on 3.1.2.rc0.

[mhansen]

On bsd

sage: var('y')
y
sage: %time p = plot3d(x^2*y,(-1,1),(-1,1))
CPU times: user 0.16 s, sys: 0.08 s, total: 0.24 s
Wall time: 0.78 s
sage: %time p = plot3d(x^2*y,(-1,1),(-1,1))
CPU times: user 0.14 s, sys: 0.06 s, total: 0.21 s
Wall time: 0.44 s
sage: %time p = plot3d(x^2*y,(-1,1),(-1,1))
CPU times: user 0.15 s, sys: 0.07 s, total: 0.22 s
Wall time: 0.48 s

[mabshoff]

This is very strange to say the least:

sage: time p=plot3d(sin(sin(x) + y^2),(-1,1),(-1,1))
CPU times: user 0.34 s, sys: 0.08 s, total: 0.42 s
Wall time: 3.07 s
sage: %time p = plot3d(x^2*y,(-1,1),(-1,1))
CPU times: user 0.16 s, sys: 0.06 s, total: 0.22 s
Wall time: 1.61 s

I must have started an old Sage. If someone can reproduce this with Sage 3.1.2.rc0 or later please give detailed information how to reproduce this. Fixed.

Cheers,

Michael

[jwmerrill]

I just reproduced this problem on a freshly built 3.1.2.rc1, on OS X 10.5.4 intel macbook. All I did was start sage in the terminal:

sage: version()
'SAGE Version 3.1.2.rc1, Release Date: 2008-09-08'
sage: var('y')
y
sage: plot3d(x^2*y,(-1,1),(-1,1))

This is still going 5 minutes later. There is a process called lisp.run eating up about 90% of my processor power, with memory usage steady around 17 MB. The same thing happens in the notebook. Pressinc ctrl-c gives

Control-C pressed.  Interrupting Maxima. Please wait a few seconds...

Which also seems to persist indefinitely. I eventually killed things by closing the terminal window.

Here's something else that takes virtually no time to run:

sage: plot3d(x^2*y,(x,-1,1),(y,-1,1))

But these commands also run indefinitely

sage: plot3d(x + y,(-1,1),(-1,1))
sage: plot3d(y*x,(-1,1),(-1,1))

[mabshoff]

The problem here is likely a clisp linked against either the system or a MacPorts/Fink? libpng.dylib. Various people have attempted to reproduce this problem and have failed. So I am closing it as invalid since one can no longer build with MacPorts/Fink? in $PATH.

Cheers,

Michael