Re: [sage-support] Re: adding noise
On Apr 2, 2010, at 9:41 PM, G B wrote:
Thanks for the detailed response, Simon. Please understand that I'm
not being critical of Sage-- quite the contrary, I'm excited about
what it might offer me once I master it.
I think you touch on one key to the problem-- I'm not a
mathematician, I'm an engineer. While most of the world would
certainly accuse us of being sloppy dressers, mathematicians are one
of the few groups that can legitimately accuse us of being sloppy
thinkers. I think that brand of sloppy thinking is what is at issue
here, and when I say work around I mean become tolerant of.
Sage has already encouraged me to learn more about ring theory than
I ever would have needed otherwise, but getting completely different
results when executing plot(f(x),(x,0,2*pi)) vs. executing plot(f,
(0,2*pi)) started playing on my patience a bit and has me wondering
if I'm simply using an irreconcilably wrong tool for the job. I
think the intention of both of those statements is the same, and
thus should yield the same result, and my suspicion is that the
reason they don't is an artifact of the plumbing, but I may be
missing something.
A good way to think about it is this: Python expressions are evaluated
greedily, from the inside out. Thus
sage: plot(f(x),(x,0,2*pi))
is the same as
sage: A = f(x)# A is now sin(x) + 0.619...
sage: B = (x,0,2*pi)
sage: plot(A, B)
When you write something like sin(x), sin is actually getting called
with the argument x, and the result is sin evaluated at the
indeterminate x (in other words, it's not just returning the old thing
back again). As a more concrete example.
sage: g(x) = sin(x) + sqrt(x)
sage: g(x)
sqrt(x) + sin(x) # g was called with x and plugged in x for x
sage: g(5)
sqrt(5) + sin(5)
sage: var('y')
y
sage: g(y)
sqrt(y) + sin(y)
sage: g(x+y)
sqrt(x + y) + sin(x + y)
It's not the f(x)=sin(x)+T.get_random_element() form that troubles
me though, for the record, I did try 'f(x)=sin(x)
+T.get_random_element(x)'. Expectedly, it doesn't like having an
unwanted argument shoved down its throat.
What still feels awkward to me is how constructs like this behave:
var('x')
T=RealDistribution('gaussian',1)
f=lambda x: T.get_random_element()
g(x)=sin(x)+f(x)
To my mind, the way that is handled is particularly confusing.
[f(1),f(2),f(3)] -- [-0.568652852118, 0.912307924442, 1.35997405644]
but,
[g(1),g(2),g(3)] -- [sin(1) - 0.176035204293, sin(2) -
0.176035204293, sin(3) - 0.176035204293]
In other words, calling f repeatedly gives different results each
time, but calling g repeatedly does not.
That may be a case where the parenthetical syntax conspires with the
overloaded meanings of function to expose my sloppy thinking, but
it also kind of looks like a trap waiting to be triggered.
If sin(x) and f(x) are fundamentally different entities, and my
engineering mind isn't completely convinced that they should be,
Yes, they are very different. The first are expression-like
functions, where it makes sense to differentiate, integrate, typeset,
and otherwise manipulate them as mathematical objects. Sin falls
into this category. The other type are procedures which are are
really arbitrary chunks of code which are the ones native to Python
(and essentially every other procedural programming language). These
are the ones that generate random numbers, test for primality, fetch
webpages, save files, etc. Plot itself is such a function. It
doesn't makes much sense to differentiate or typeset such functions,
but they can be called.
Both types of functions are clearly essential, the confusion arises in
the fact that it's possible to evaluate (and, sometimes, plot) both
kinds. That being said, I think it should easier (and more natural) to
try to do what you're trying to do here.
then the syntax should prevent the construction of g in such a
manner. Either execution of f should be deferred until g is called
with a parameter, as I would expect, or an error should be thrown
for providing illegal arguments to operator '+'.
The problem is that the two terms are evaluated before the + operator
is hit, i.e.
sage: g(x) = sin(x) + f(x)
is the same as
sage: A = sin(x) # actually calls sin (resulting in sin(x))
sage: B = f(x) # actually calls f (resulting in 0.619)
sage: g(x) = A + B # tries to add (which is just fine)
If I want g(x) defined as sin(x) plus the result of f(x) as x is
defined at the definition of g, then the syntax should highlight
that by forcing something like g(x)=sin(x) + `f(x)`
To get something deferred, which sounds like what you want, you could
abandon the g(x) = ... syntax completely and always use lambda (or def)
sage: g = lambda x: sin(x) + f(x)
or
sage: def g(x):
...return sin(x) + f(x)
It may take some getting used to, but functions can even return other
functions. For example, you
[sage-support] Re: Print only outputs?
Another solution, different from the previous ones is to convert sws file to pdf using sws2tex - http://bitbucket.org/whuss/sws2tex/ It should be trivial to hack the python or TeX code to remove the content of input cells. example of the output is http://user.mendelu.cz/marik/sage/as.pdf Robert Marik On 1 dub, 19:27, Eugene Goldberg omegat...@gmail.com wrote: Hi! Is it possible to print only output content of worksheet? -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] List of standard functions?
I screened all of the offered documents from the sgaemath-page to find a list of the offered standard-functions - no success! May be there is a table or list about that but I just could not find it? Screening the index is one possibility, but does not make me really happy. Tnx BB -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
Re: [sage-support] List of standard functions?
Hi, Do you mean something like these: http://wiki.sagemath.org/quickref ? Otherwise, the reference manual http://sagemath.org/doc/reference/ has a full list. On Sat, Apr 3, 2010 at 11:32 PM, bb bblo...@arcor.de wrote: I screened all of the offered documents from the sgaemath-page to find a list of the offered standard-functions - no success! May be there is a table or list about that but I just could not find it? Screening the index is one possibility, but does not make me really happy. Tnx BB -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.comsage-support%2bunsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject. -- Tim Joseph Dumol tim (at) timdumol (dot) com http://timdumol.com -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: List of standard functions?
Hi! Question out of ignorance: What do you mean by a 'standard function'? Is it calculus stuff such as sin and cos, or do you mean Python functions? If it is the latter, you may get a list of all callable objects in the global name space by sage: F = [f for f in globals().values() if callable(f)] If it is the former: Sorry, I am more into algebra, and mathematically I am no friend of standardised knowledge. Best regards, Simon -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] Re: List of standard functions?
On Apr 3, 11:55 am, Simon King simon.k...@nuigalway.ie wrote: sage: F = [f for f in globals().values() if callable(f)] I would write it as filter(callable, globals().values()) Alec -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] operands and expresssion
let us do,
f=function('f',x)
expr=f(x)
expr.operands()
the out put is,
[x]
Is it a bug?, I expect [f(x)].
using,
f=function('f',x)
expr=2*f(x)
expr.operands()
correctly gives,
[f(x),2]
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[sage-support] derivative instance
Is there any way to check whether a symbolic expression is a derivative. Like, isinstance(diff(f(x),x),what to put?) gives True and isinstance(f(x),what to put?) gives false, assuming f is not a derivative itself. -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
Re: [sage-support] operands and expresssion
On Sat, Apr 3, 2010 at 11:15 AM, pallab pallabb...@gmail.com wrote:
let us do,
f=function('f',x)
expr=f(x)
expr.operands()
the out put is,
[x]
Is it a bug?,
No, it's not a bug since the operator is the function f:
sage: f.operator()
f
--Mike
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[sage-support] Re: derivative instance
What kind of behavior do you expect from the following command? isinstance(diff(sin(x),x),what to put?) Robert On 3 dub, 20:32, pallab pallabb...@gmail.com wrote: Is there any way to check whether a symbolic expression is a derivative. Like, isinstance(diff(f(x),x),what to put?) gives True and isinstance(f(x),what to put?) gives false, assuming f is not a derivative itself. -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: sageplot and includegraphics3-... SOLVED
Hi Dan and Georg
On 1 dub, 01:37, Dan Drake dr...@kaist.edu wrote:
Ah, this is very nice. I was going to reply and say that rewriting
\sageplot to parse things like \sageplot-3{...} would be very hard
(for me, at least; I'm not much of a TeX guru) but now I can put a
reference to this into the SageTeX manual.
I can help you to find the correct redefinition of sageplot command,
if you are interested. It should be also simple to do this
automatically by SageTeX whenever beamer class is used. But I think
that this is not a good method. WHY? If the slide contains 10 layers
and we put the graphics from the third layer, we have to generate the
graphics file 7 times! We end up with 7 identical pictures which slow
down the compilation by Sage and the resulting PDF file is too big.
The user should be encouraged to prepare pictures for PDF presentation
separately and use a convenient method to insert these pictures. For
example, there are methods which insert a picture in PDF file only
once, even if it is used on many places. But these topics are not
related to Sage and should be probably discussed somewhere on TeX
group.
Robert
Dan
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[sage-support] Re: derivative instance
I do not know. If it is already evaluated to cos(x) then it should be true. current sympy gives false, I think I would go with it. On Apr 3, 11:36 am, ma...@mendelu.cz ma...@mendelu.cz wrote: What kind of behavior do you expect from the following command? isinstance(diff(sin(x),x),what to put?) Robert On 3 dub, 20:32, pallab pallabb...@gmail.com wrote: Is there any way to check whether a symbolic expression is a derivative. Like, isinstance(diff(f(x),x),what to put?) gives True and isinstance(f(x),what to put?) gives false, assuming f is not a derivative itself. -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] Re: derivative instance
I mean... I do not know. If it is already evaluated to cos(x) then it should be false (not *true*). current sympy gives false, I think I would go with it. On Apr 3, 11:51 am, pallab pallabb...@gmail.com wrote: On Apr 3, 11:36 am, ma...@mendelu.cz ma...@mendelu.cz wrote: What kind of behavior do you expect from the following command? isinstance(diff(sin(x),x),what to put?) Robert On 3 dub, 20:32, pallab pallabb...@gmail.com wrote: Is there any way to check whether a symbolic expression is a derivative. Like, isinstance(diff(f(x),x),what to put?) gives True and isinstance(f(x),what to put?) gives false, assuming f is not a derivative itself. -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: derivative instance
On Apr 3, 2:32 pm, pallab pallabb...@gmail.com wrote: Is there any way to check whether a symbolic expression is a derivative. Like, isinstance(diff(f(x),x),what to put?) gives True and isinstance(f(x),what to put?) gives false, assuming f is not a derivative itself. One can do the following, for example, def is_diff(expr): try: return isinstance(expr.operator(), sage.symbolic.operators.FDerivativeOperator) except (AttributeError): return False Alec Mihailovs -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] Re: Print only outputs?
On Apr 2, 11:47 pm, William Stein wst...@gmail.com wrote: That's pretty clever! Thank you! Is amazing how flexible the notebook is, since it uses HTML instead of ReST... (yes, I know, it's flexible enough to support cross-site scripting attacks too). That's the same as with other CAS. In particular, I can write a line of code in the Maple worksheet, with autoexecute, which would format the hard drive (erasing all files on it), immediately after opening that worksheet, and there nothing could be done by the person opening that worksheet to prevent that (other than opening it in a secure mode, i.e. with switch -Z if I remember correctly, which not that many people use.) Alec -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
[sage-support] Is there any way to get old VMware versions?
I've officially given up on ever getting VirtualBox to work properly on my netbook (I'm pretty sure it's just a memory issue), so I'd like to go back to the last VMware version (4.1.2, I guess). I can find where to find the source code for the old versions, but I've looked all over sagemath.org and can't find anywhere to download prebuilt copies. I suppose it has to be possible theoretically to build it from source, but that type of stuff is well beyond me. Is there anyway to get a copy of 4.1.2? Or, alternately, a very detailed list of instructions written for total idiots describing how to create one from the source code? -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject.
Re: [sage-support] Is there any way to get old VMware versions?
Hi, Coincidentally, I gave up on using virtualbox for sage-windows. The next version will be vmware based. Expect this early next week. On Saturday, April 3, 2010, Rob furit...@gmail.com wrote: I've officially given up on ever getting VirtualBox to work properly on my netbook (I'm pretty sure it's just a memory issue), so I'd like to go back to the last VMware version (4.1.2, I guess). I can find where to find the source code for the old versions, but I've looked all over sagemath.org and can't find anywhere to download prebuilt copies. I suppose it has to be possible theoretically to build it from source, but that type of stuff is well beyond me. Is there anyway to get a copy of 4.1.2? Or, alternately, a very detailed list of instructions written for total idiots describing how to create one from the source code? -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org To unsubscribe, reply using remove me as the subject. -- William Stein Associate Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
[sage-support] Re: operands and expresssion
I got it :), thanks.
On Apr 3, 11:34 am, Mike Hansen mhan...@gmail.com wrote:
On Sat, Apr 3, 2010 at 11:15 AM, pallab pallabb...@gmail.com wrote:
let us do,
f=function('f',x)
expr=f(x)
expr.operands()
the out put is,
[x]
Is it a bug?,
No, it's not a bug since the operator is the function f:
sage: f.operator()
f
--Mike
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[sage-support] Re: Is there any way to get old VMware versions?
I'm VERY glad to hear that. I'll hang on until the next release then. Thanks! On Apr 3, 6:13 pm, William Stein wst...@gmail.com wrote: Hi, Coincidentally, I gave up on using virtualbox for sage-windows. The next version will be vmware based. Expect this early next week. On Saturday, April 3, 2010, Rob furit...@gmail.com wrote: I've officially given up on ever getting VirtualBox to work properly on my netbook (I'm pretty sure it's just a memory issue), so I'd like to go back to the last VMware version (4.1.2, I guess). I can find where to find the source code for the old versions, but I've looked all over sagemath.org and can't find anywhere to download prebuilt copies. I suppose it has to be possible theoretically to build it from source, but that type of stuff is well beyond me. Is there anyway to get a copy of 4.1.2? Or, alternately, a very detailed list of instructions written for total idiots describing how to create one from the source code? -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group athttp://groups.google.com/group/sage-support URL:http://www.sagemath.org To unsubscribe, reply using remove me as the subject. -- William Stein Associate Professor of Mathematics University of Washingtonhttp://wstein.org -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
