## Maple 17 Questions and Posts

##### These are Posts and Questions associated with the product, Maple 17

I created a null tetrad, but Maple's GRQuery returns false.  Here is the code:

## problem with solve...

Hello! I have the task to calculate the two angles of an 3d linkage. now in step 11 i have these two equations:

I have to solve these for phi, that is the angle I'm looking for. But the solution for phi should be indepented of psi. alpha and beta are variables. Everything else are known constant values.
What I tried: I solved Gl7 for psi (step 12...

## use of map and map2...

Hi all,

#####################################
myp:=proc(a,b,c)

local ans;

ans:=zip(`+`,a,b);

ans:=ans*c;

return ans;

end proc;
myp([\$1..4],[x,y,z,w],2);
map2(myp,[\$1..4],{[x,y,z,w],[x2,y2,z2,w2],[x3,y3,z3,w3]},4);

map2(myp,[\$1..4],{[x,y,z,w],[x2,y2,z2,w2],[x3,y3,z3,w3]},10);
map2(myp,[\$1..4],{[x,y,z,w],[x2,y2,z2,w2],[x3,y3,z3,w3]},0.5);

#####################################

Is it possible to use something like

## More efficient way? (quicker, less memory used, go...

Hi all,

##################################################################

restart:

K:=50;C:=20;

st:=time():

for j from 2 to K do
for c to C do
solve({log(cat(p,j,'C',c)/(1-cat(p,j,'C',c)))=mu+cat(tau,j)+cat(eta,c)+cat(mix,j,c)},cat(p,j,'C',c));
assign(%);
...

## Integral that Maple 17 cannot compute

by: Maple 17

Hi,

Here an example of integral that Maple 17 cannot calculate (mean of standard Gumbel distribution)

> G:=int(x*exp(-x)*exp(-exp(-x)), x = -infinity .. infinity);

The result is known as the Euler-Mascheroni constant as shown by a numerical computation:

> evalf(G);

0.5772156649

>  identify(%, extension = [gamma]);

gamma

> evalf(gamma)

0.5772156649

Also, it cannot compute the variance

## Import string and numerical data from txt.file...

Good morning everbody,

I am currently trying to get string and numerical datas from a txt.file but I don't get how to do this.
I have done this in matlab but I would like to make it in maple.
I have read other post about the subject and try tried this command:

``` fd := fopen(dataFile,READ,TEXT):
fclose(fd):

A:=convert(theData,Array);but it didn't help me. ```

## Can WARNINGs be detected?...

Is there any way to detect programmatically that a WARNING has been issued? A method that converts WARNINGs to errors would be acceptable.

## Difference between these Matrices?...

Hi all,

restart:
a:=<1,2;3,4>;
whattype(a);
b:=Matrix(2,2,[1,2,3,4]);
whattype(b);
evalb(a=b);

Is there any real difference between these two methods of creathing matrices?

How do I check if two matrices are equal?

Thanks,

Casper

## plot function does not accommodate parameter range...

I'd like to be able to plot a function that not only has a range for the dependent variable(s) but also for any "variable constants" that may be in the expression.

For example, if I wanted to plot the following expression :

y = A sin(wx + c)

and also to explore its behaviour over the following ranges for A, w and c :

## Name of equation with spaces...

Hello!

It seems there's some problems with spaces in the name of equation

As you can see the 'SOLVE' command can't substitute variable 'b' in my example, if 'b' variable wasn't defined BEFORE the equation with spaces in its name....

## Embedding an animation/video in a pdf...

I am wondering if there is a way to create a pdf from a Maple worksheet that has an animation, or in the case of Maple 17, a video, that allows the viewer of the pdf to play the animation/video.

Thanks!

## getting sum of all elements in a Matrix...

Hi all,

I am trying to get the following matrix:

restart:
int00:=Matrix(3,3);
int00[2,2]:=a;
int00[2,3]:=b;
int00[3,2]:=c;
int00[3,3]:=d;
int00;
cols:=MTM:-sum(int00,1);
rows:=MTM:-sum(int00,2);
int00[1,1..3]:=-cols:
int00[1..3,1]:=-rows:
int00;

int00[1,1]:=a+b+c+d:
int00;
MTM:-sum(int00,1);
MTM:-sum(int00,2);

How do I get the sum of all elemnets in the 'original' matrix? Bascially, the int00[1,1] term in the toy example.

## Using Maple to find Newman-Penrose equations with ...

I just bought Maple 17 and tried to find a couple of Newman-Penrose spin coefficients.  I can do it by hand, but when I try to do the same thing using Maple I am stuck.  Maple lets me define an orthogonal tetrad, then I convert that to a null tetrad.  But how do I then fiind spin coefficients?  I know Maple has an entire list of metrics (385) already loaded, but I need to investigate different Petrov types to develop a metric.  Thanks.

## New in Maple 17: Parallel Garbage Collector

by: Maple 17

For the last few releases of Maple, we have been adding features to take advantage of multi-core processors.  Most of this work has focused on particular algorithms or on tools that allow users to author their own parallel code.  Although this was very useful for those users who were able to use those tools, many users did not see a performance improvement.  To help all users we need to integrate parallelism into the core algorithms of Maple.  In Maple 17 we have taken the first step towards general parallelism in the core algorithms by implementing a parallel garbage collector.

## series expansion factor missing?...

r1:=2*(1-s^2)^(1/2)*arctanh((1+s)*tanh(x)/((1-s)*(1+s))^(1/2))/((1-s)*(1+s))^(1/2)+ln((1/2)*arccosh(1/s)-x)

with x=1/2*arccosh(1/s)-beta*u

is to be calculated to the first order in u.

in fact im only interested in the first order not in the zero order.

so when applying the series I get for the first order

-beta*u/sqrt(1-s^2)

whereas by hand I get:

-beta*u*s/sqrt(1-s^2)

I'd really appreciate some idea since...

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