Inspired by my own post The art of linking, I here bring an expanded version (I hope that it does not appear too self-centred to do so): You can link to other parts of MaplePrimes, or to external webpages, using the HTML tag a with its associated attribute href. This tag and its attribute you may enter by pressing the link-image  (please disregard the black background), which is located above the area where you enter your text, the result being <a href="http://"> The part between the two "'s is where the address of your link, the socalled URL (Uniform Resource Locator) must be inserted. Below, four typical link situations are treated:

• Linking to a thread: Taking as an example the thread in which the above post appears, you could write (for long URL's, as this one, use copy-paste to avoid typos) <a href="http://www.mapleprimes.com/forum/why-does-evalb-evalf-10-0-evalf-10-0-float-1-0-30-false">The other thread</a> which would appear on the screen as The other thread.
• Linking to a specific post: Each post in MaplePrimes has its own unique ID. It can be found by placing the mouse over the link email this comment of the post to which you want to link, and then reading of a five-digit number at the end of the line at the lower left of your screen (in Microsoft Internet Explorer). A link to that post is then created by appending to the URL of the thread itself the following code: #comment-....., where for ..... the five-digit ID has to be inserted. It was William Spaetzel who originally told me this. Taking as an example the above post, which has the unique ID 11566, you could write <a href="http://www.mapleprimes.com/forum/why-does-evalb-evalf-10-0-evalf-10-0-float-1-0-30-false#comment-11566">The other post</a> which would appear on the screen as The other post.
• Linking to or showing a picture: First of all you have to upload your picture using my files under Navigation. Having done so you can copy-paste the text in the column Download Link Code. This text contains both the HTML a and image tags. You can then choose to keep the full text, thereby having a clickable image (a link to the image), or you can manually strip away all a tags (remember the ends also) thereby having a non-clickable picture, as I have above.
• Linking to an external web page: Taking Maplesoft as an example, you could write <a href="http://www.maplesoft.com/">Maplesoft</a> which would appear on the screen as Maplesoft. The part target='_new' has been automatically inserted by the MaplePrimes system (click on Input format, which is located below the input text area, to see the various input formats), and so it need/should not be entered manually.

Yesterday evening I decided that I would like to make a list of links to the posts of mine which I consider most valuable. Today, however, I have realized that this is no easy task because the closest I can get to these posts is the "my recent posts" where only links to complete threads can be found. Therefore, would it be possible to get a list of ones own posts, each post with a pointer to its appropiate place in some thread? I guess that it boils down to some appropiate database query.

Hmmm. How did eTwqgQegPG manage to accumulate 246 points in less than 2 days? Without posting anything?

Maple 11 generously introduced the option smooth=true to listdensityplot. But I am finding unexpected behavior with the option. In the code below, notice how the option smooth=true ends up triggering the transform "Scale" to produce a three-dimensional plot structure, but the option smooth=false, in conjunction with "Scale", produces (as expected) a two-dimensional plot structure. Code follows: with(plottools):with(plots): sample:=[seq([seq(i*j,i=1..40)],j=1..40)]: Grid:=listdensityplot(sample,smooth=true,colorstyle=HUE,style=patchnogrid); display(Grid); Scale:=transform((x,y)->[x*2*Pi/40,y*Pi/40]):

My Calculus III students stumbled on this buggy thing while evaluating a line integral to calculate the flux The curve [X(t),Y(t)] is the right-half of a Lemniscate with polar equation R^2=cos(2*theta). The vector field is F(x,y)=M(x,y)i+N(x,y)j. They were integrating M*dy-N*dx around the curve. If we let a=M*dy and aa=expand(M*dy), then they find that Maple's int gives inconsistent results. As far as I can tell, a and its twin aa are well-behaved over -Pi/4..Pi/4 and equal. Maybe it is a bug in how Maple handles elliptic integrals? Or maybe it is some issue with removable discontinuities?

We are pleased to announce the winners of the monthly Maple Mentors Awards for October and November. The winner for October is Douglas Meade and Georgios Kokovidis has won for November. Douglas Meade and Georgios Kokovidis will receive a prize of their choice to thank them for their involvement with the MaplePrimes community. We have received many emails nominating these individuals. One member had this comment concerning the help given by Douglas Meade:

I was writing a small procedure to generate random points on the unit sphere. The details are not directly relevant here, but the procedure was as follows.

randspherepts := proc(n::nonnegint, d::posint) 
 local i, p, r; 
 description "Returns co-ords of n random pts on the d-dimensional unit sphere [Knuth, 1998: sect. 3.4.1E]"; 
 uses ArrayTools;
 p:= Matrix(n, d, RandomTools:-Generate('distribution(Normal(0,1))', makeproc=true),datatype='hfloat',order='C_order');
 r:= ElementPower(AddAlongDimension(ElementPower(p,2),2),1/2);  
 seq(ElementDivide(p[i,1..-1],r[i]), i=1..n) 
end proc;

Using MAPLE V, Release 11, a creep curve has been formulated, which represents the mechanical behavior of metals, polymers, and ceramics, for instance.

Inspired by the post Re: the physics package I decided to have a closer look at the function FeynmanDiagrams. As the Lagrangian I thought I might as well take the QED Lagrangian for a massless spinor field Q[i](X) coupled to an external electromagnetic field A[mu](X):

restart:
with(Physics):
Setup(advanced):
L_QED :=
   +Dagger(Q[i](X)) * Dgamma[4] * Dgamma[mu][i,j] * I * diff(Q[j](X),X[mu])
   +Dagger(Q[i](X)) * Dgamma[4] * Dgamma[mu][i,j] * e * A[mu](X) * (Q[j](X));

Can someone explain why is 0 handled differently by evalf[10] than nonzero numbers in the following examples? Digits:=50: epsilon:=Float(1.0,-30); -30 1.0 10 for x in [0,0.0,1,sqrt(2),Pi] do x,evalb(evalf[10](x)=evalf[10](x+epsilon)); od; 0, false 0., false 1, true (1/2) 2 , true Pi, true

In trying to answer the second question in How to determine the order of an ODE? I have unsuccessfully tried to use select to filter out the appropiate parts of the differential equations. In these attempts I have hit upon a behaviour of select I do not understand: In my opinion each of the following two code lines (or at the very least the second line) should return the differential expression itself:

select(has,diff(y(t),t),y);
select(has,diff(y(t),t),y(t));

But they do not; each line returns diff(y(t)), where the variable t with respect to which is being differentiated is missing. Why? Is it just me having fundamentally misunderstood something?

So what is the best way to put a "link" from one place in a maple document to another. So that someone can jump quickly when clicked? Thanks!

I recently changed the system from 10.4.10 to 10.4.11 and not too long afterwards noticed the following problem: when I restart my machine the maple 9.5 does not load properly. It takes about three restarts to get maple to open. Any suggestions?

The following is the code for the 2nd Fick's law with initial/boundary conditions. Unfortunately this code does not show me the result required for next process. It would be useful for us to proceed this work. Thanks in advance. ( Currently we are using Maple 10.) > restart; > DiffusionCoefficientST := 0.5e-2; > ExperienceConstant := 5; > Temperature := 273+25; > PDE := diff(C(x, t), t) = > DiffusionCoefficientST*(exp(1))(-ExperienceConstant(1/Temperature-1/296))*(­diff(C(x, > t), x, x)); > IBCondition := {C(x, 0) = 2, C(0, t) = 0, ((D[1])(C))(5, t) = 0}; > pds := pdsolve(

Maple 11 has been working flawlessly for me under Mac OS X Leopard, with both updated. However, while the screen output appears to be fine, the Times New Roman (and other?) fonts seem to disappear and are replaced by a sans serif font (like Helvetica or Geneva). This occurs whether I send the output to a postscript laser printer (HP 2200) or to a non-postscript inkjet (HP 5550). I vaguely remember having a similar problem years ago, i.e., prior to Mac OS X. Has anyone else encountered this problem? Has anyone who encountered this identified a solution? So far, I'm stuck exporting my resu