Dear All

I have an numerical integral to solve over set of 10 discrete values. The problem is, this integral have two dependent variables. Please see following:

Numerical_Integration.mw

Download Numerical_Integration.mw

Regards

I want to plot a function given different value combinations of parameters. I used the following code and it doesn't work. Could anybody please help?

I have lots of subsections for organization and have all the outputs at the end...  is there any way to force all/any sections/subsections to remain closed while the whole page is being evaluated? I still want the section to evaluate, but I want it to stay closed.

Every time I try to type in a procedure I get the error:  

Error, unterminated procedure

immediately after typing in the first line.  How can I type in the remaining lines of my procedure?

Note:  in maple 7 (years ago) I never had this problem.

How can i find the critical points of any cubic polynomial in maple17? I want a general procedure

Hi !

I have trouble to do this stuff :

i am solving an ODE and i would like to use the result as a function.

example :

>>ode := diff(f(x), x) = 2*x+6;
                        d                
                       --- f(x) = 2 x + 6
                        dx               
>>init := f(0) = 12;
                           f(0) = 12
>>dsolve({init, ode});    
                      f(x) = x  + 6 x + 12

Here everything works fine...

but now i want to define g(x) = f(x)*exp(x) ...

but i can't use g(x) after :

like :

>> g := x -> f(x)*exp(x) ;
                          x -> f(x) exp(x)
g(2);
                          f(2) exp(2)
f(2);
                              f(2)

How can i do that please ??

Thanks,

Corentin

Hi Maple People

# Some Maple code
restart
x:= Vector(10):
y:= Vector(10):

for z from -5 to 4 do
   x[z+6]:=z^2 + 40:
   y[z+6]:=z^2 + z + 41:
end do:

plot(x,y,style=point,symbol=asterisk)

Regards

Matt

hi.i am a problem with calculate numeric integral.

please help me

thanks

Float(undefined).mw

I want to make sense of the expression

Int(t^2/ln(t)*exp(-t), t=0..infinity);

The denominator vanishes at t=1.  The singularity at t=1 is not integrable.  I want to see whether the integral is defined in the sense of Cauchy principal value.  Thus, I let

K := Int(t^2/ln(t)*exp(-t), t=0..1-a) + Int(t^2/ln(t)*exp(-t), t=1+a..infinity);

and wish to see whether the following limit exists:

limit(K, a=0, right);

Maple cannot evaluate this.  Nor can I.  Alternatively, we may try:

series(K, a=0);

or

series(K, a=0) assuming a>0, a<1;

In both cases Maple says that it is unable to compute the series.

So my question is: Does the Cauchy principal value exist, and can Maple help one to determine that?

For my task I have to solve inequalities in the form

With z being an expression yielding a complex number, but taking a real number as argument. Maple does not give any results when I pass such an expression to the function solve. It just immediately returns without any output.

What can I do to get the solution?

Hej Mapleprimes,

I am making Maple sweat over a simple problem

11.00=11.244522435+log(x) 

right click and solve for variable x. 

So far Maple has been working for 10 minutes at allocatet 2 GB 

memory.  And no answer yet. 

Is there a short way to solve this faster?

Kind regards 

Per Kirkegaard

Hy

I have a list

A:=[[2,1],[1,2],[3,5],[7,6]]

I want to be able to tell what position the element [3,5] is in the list

I'm using

member([3,5],A,'t')

is there anything faster

maybe instead of storing as a list, I can use rtables or something?

thankyou for your time

Hi,

I'm trying to fill an Array but I don't know the correct syntax, and Maple help isn't much use.

How do I form an Array, A, which has 10 rows and 2 columns. Where one column is say the row number squared and the other column is the row number cubed. 

So A would be:

[1 1]
[4 8]
[9 27] .....

Also, I'm using the square and cube numbers as an example. But is there a general format for doing this, whatever the values I want to put in the array are?

Thanks

I am faced by the problem where I used Grid:-Seq()---locally---to do some long time computation and I am faced by the exhaustion of memory problem. I think the problem itself is related to the memory management in maple.

So the problematic function is

# Procedure: ComputeEventsCTypeGrid
#   Compute events such that three quadrics intersects in a point.
#
# Parameters:
#   Q          - a set of quadrics
#
# Output:
#   Indexes of quadrics which intersect in a point.
# TODO:
#  - Memory
#  - Cleanups
ComputeEventsCTypeGrid := proc( Q )
  local s, cType, i, j, k, rootNb, univ, sys;
  s := proc (i, j, k)
    sys := [ Q[i], Q[j], Q[k] ];
    univ := PolynomialIdeals[UnivariatePolynomial]( indets( sys )[1], sys );
    if not type( univ, constant ) then
      rootNb := nops(select(proc(x)op(x)[2]>0;end proc,RootFinding:-Isolate( univ, [ op( indets(univ ) ) ] )) ):
      if rootNb > 0 then
        return [ univ, rootNb, sys ];
      end if:
    end if:
  end proc;
  cType := [Grid:-Seq(seq(seq(s(i,j,k),k=j+1..nops(Q)),j=i+1..nops(Q)),i=1..nops(Q))];
  return cType;
end proc:

A dump from top after calling ComputeEventsCTypeGrid for some data(total amount of memory on this machine is 251G + 48G swap)

VIRT    RES    SHR S  %CPU %MEM     TIME+

33.007g 0.031t   3676 S   0.0 12.5   2606:20
31.137g 0.029t   3436 S   0.0 11.7   2274:34
8645756 4.984g   2840 S   0.0  2.0  32:06.40
28.798g 0.026t   1968 S   0.0 10.7   1821:16
26.650g 0.024t   1968 S   0.0  9.8   1520:54
25.346g 0.023t   1968 S   0.0  9.2   1236:44
23.296g 0.021t   1968 S   0.0  8.4   1004:52
20.498g 0.018t   1968 S   0.0  7.4 790:30.81
16.799g 0.014t   1968 S   0.0  5.9 625:28.12
15.011g 0.013t   1968 S   0.0  5.2 469:36.27
7678444 4.149g   1968 S   0.0  1.6 104:34.22
6734804 623904   1968 S   0.0  0.2  73:13.13
4327420 132516   1968 S   0.0  0.1  24:11.51
3420712 111336   1968 S   0.0  0.0  11:26.16
13.671g 0.011t   1964 S   0.0  4.6 380:15.13
11.771g 9.831g   1964 S   0.0  3.9 274:25.59
9936056 7.769g   1964 S   0.0  3.1 201:13.94
8805512 3.394g   1964 S   0.0  1.3 148:09.53
5077056 1.500g   1964 S   0.0  0.6  42:19.29
2384784  82040   1832 S   0.0  0.0   3:56.57

Size of output data calculated with

> length(sprintf("%m", eval(cType)));

> 326260610

Also, I called gc() at the end of the computations but memory allocated by instances of mserver were not released. Does it mean gc() should be called from each instance separately? My final point is that I have to run some other calculations for different and bigger dataset (It will probably take 2 days to finish -- Q has around 700 polynomials of degree 2) and for this moment I cannot do this because I've gotten an error about not enough amount of memory.

I have 2 questions.

1) The help pages discuss the use of functions described by piecewise when using dsolve. The examples are clear enough but nothing is said about using the numeric option and piecewise. I get an error message for a very simple example: y' +R(t) y^2 = 0. Are I correct in assuming that dsllve numeric cannot deal with piecwise continuous functions?

2) I tried to solve a system of 2 second order constant coefficient linear ODEs using dsolve. After a very long wait (over an hour) I gave up. I tried again using "method=laplace" and got an instant answer. I did not bother to mention it here but it occurred again, this time with a fourth order and second order constant coefficient system. Very strange! I know that the laplace transform is a very useful tool; shouldn't Maple also know that?