Bonjour,

It seems that bit to bit functions on integers, like the C-functions and, or, not, xor, << (left shift) , >> (right shift), are missing in Maple.
 

Why?

> 8 and 25;
Error, invalid boolean expression

GraphTheory includes ImportGraph and ExportGraph.  These are handy functions but they would be much more useful if they supported GraphML.  GraphML is a popular standard.  It is particularly useful for integration with tools built with the Prefuse API (http://prefuse.org/).  Please add GraphML support for importing and exporting Graphs.

Hi,

I have a dual processor computer and I am using Maple 8 (because it is much faster than Maple 11) but I noticed that Maple 8 only maxes out one processor and doesn't use both.  I am using (unfortunately) Windows Vista.  I would appreciate any suggestions.

I also have a single 2.3 GHz processor at home with XP so I'll give that a try.

Thanks

For a bit of light relief, head on over to the online comic strip at phdcomics.com.  If you've ever been a PhD student, be careful, this strip might make the nightmares come back...

Hi.

I think there is a problem with arrays. When i define an array like this:

A := {1,12}
Then it works fine as you can see:
print(A[1])=1
print(A[2])=12

but if i do it like this:
A := {1.1,12}
Then the results is reversed:
print(A[1])=12
print(A[2])=1.1

I'm running Maple 11 and updated to the 02 patch.

When I try to integrate a function,Maple returns a summation sign and underneath this sign is the expression R= RootOf (      ),where the bracket contains a cubic polynomial written in terms of Maple's internal default variable _Z.  Why can't Maple simply evaluate the roots of this cubic equation and return the value to me? What do I have to do to force Maple to return the desired result? 

AntipodeanMan

Hello,

I have problem with define external function with dll written in Visual Basic.

Declaration of function is

Hi there,

fsolve fails me, for the first time. I have this very messy expression, which comes out of a cubic equation. It must have a zero. I plot it and the graph, smooth, shows a zero between 16.4 and 16.5, but maple's fsolve fails to find it, why's that? The slope of the function is very flat near the zero. I tried to tell maple the solution is between 16.4 and 16.5, to no avail.

Any advice will be much appreciated. The following code tells it all.

many thanks,

Patrick.

As Demmel and others have noted, SVD is both more reliable and more expensive than QR as a method of solving rank-deficient least squares problems.

SVD is the method that LinearAlgebra:-LeastSquares will choose when the Matrix has more columns than rows (n>m), unless instructed otherwise using the optional 'method' parameter.

LinearAlgebra:-SingularValues always computes a full U and Vt. But for least squares computations, such as when n>m, this is not necessary. Including the smaller singular values may just be (re-)introducing noise. See here for more detail.

Here's a 20x2000 example, using wrapperless external calling and the SVD routine dgesvd in the CLAPACK library. The effective speedup by using the Thin SVD for that 20x2000 least squares example is about a factor of 100 (ie, 2000/20), with a similar reduction in additional memory allocation.

I am having problems using implicitplot.  I run this code and it worked and today I tried it again and it gives me the following:

with(plots,implicitplot);

implicitplot(0=int(erf(  (T-e*t)/sqrt(2)  )*t^2*exp(-t/2),t=0..infinity),e=0..1,T=0..10);

Error, (in plots/implicitplot) invalid input: the following extra unknowns were found in the input expression: {t}

The weird thing is that this worked before (took about 10min though) and now it isn't.  Any suggestions?

Thanks

May be that some other people want to use pattern-matching techniques in wrong ways or contexts. What I am interested in is much simpler and clear.

I frequently see references to data being loaded from maplesoft.112.2o7.net -- what is that?  It's annoying because the page seems to have been loaded, but the browser is still active doing stuff, so that interaction is slower.  If this is not doing something really useful, could it be turned off?

Using dsolve gives the incorrect solution unless you force it to use Laplace transforms. 

Notice that Y5 is the correct solution, not the Y coming from dsolve.

DE17:=diff(y(t),t$2)+y(t)=Dirac(t-Pi)+Dirac(t-2*Pi)+Dirac(t-3*Pi);
Y:=dsolve({DE17,y(0)=0,D(y)(0)=0},y(t));
plot(rhs(Y),t=0..6*Pi);
with(inttrans):
Y2:=laplace(DE17,t,s);
Y3:=solve(Y2,laplace(y(t),t,s));
Y4:=subs({y(0)=0,D(y)(0)=0},Y3);
Y5:=invlaplace(Y4,s,t);
plot(Y5,t=0..6*Pi);
 

Anybody run into this problem before?

I was playing with a problem from the Maple NG, one can state it as
  
  Int( arccos(x) / ( 1+x^4) , x=0 .. 1)

Maple 11.02 gives a result, which numerical can not be valid.

Using real (!) partial fractions (Maple uses decomposition over the
complex, no?) I got a similar problem with denominator = parabola
(and continuity over the integration interval):

  Int( arccos(x) / (x^2 - x * 2^(1/2) + 1), x = 0 .. 1)

Some more and time-consuming consuming experiments reduces troubles
to the following example, where symbolics are disproven by numerics: