Hey Guys, 

I was wondering how big an algebriac equation has to be before maple crashes. (i cant think of a better word) . I am trying to derive an epression that involves solving 9 equations that all pretty big. about 16 terms. I am substituting in each equation into the next and I get to the last one and it just says evaluating. I left it up overnight and it was still there evaluating. Any help would be appreciated. 

Help me with this:

I have a differential equation:  s:= diff(h(t),t) = -0.1738137398e-2/sqrt(2.8-h(t))

Solution is: h(t) = 14/5-(1/100000000)*2607206097^(2/3)*t^(2/3), h(t) = 14/5-(1/100000000)*(-(1/2)*2607206097^(1/3)*t^(1/3)-(1/2*I)*sqrt(3)*2607206097^(1/3)*t^(1/3))^2, h(t) = 14/5-(1/100000000)*(-(1/2)*2607206097^(1/3)*t^(1/3)+(1/2*I)*sqrt(3)*2607206097^(1/3)*t^(1/3))^2

And i have to need a plot... so i use complexplot and recive a mesage:

Error, (in plots:-complexplot) invalid input: `plots/complexplot` expects its 2nd argument, r, to be of type {range, name = range}, but received h(t) = 14/5-(1/100000000)*(-(1/2)*2607206097^(1/3)*t^(1/3)-((1/2)*I)*3^(1/2)*2607206097^(1/3)*t^(1/3))^2

Help me if you can!! Thank you so much!!! 

Dear,

I have a perfectly working when all parameters are known (figure 1), however I want to perform a sensitivity analysis by derivating the code if one parameter is unknown. Because of multiple possible answers and because of the complexity of the formula, I cannot run this script and get solutions. Any ideas how I can this calculation lighter so it is able to run? Values should be real and positive (so 1 or 2 solutions are the only one I'm interested in)

Any ideas, how I can make this code runnable? (file is below)

I'm stuck on this for a while now :/ So I hope someone will be able to help me

Many thanks in advance!l

Question.mw

Figure 1: [URL=http://s1240.photobucket.com/user/laggstar/media/Parameter%20f%20known.png.html][IMG]http://i1240.photobucket.com/albums/gg494/laggstar/Parameter%20f%20known.png[/IMG][/URL]

Figure 2: [URL=http://s1240.photobucket.com/user/laggstar/media/Parameter%20f%20unknown.png.html][IMG]http://i1240.photobucket.com/albums/gg494/laggstar/Parameter%20f%20unknown.png[/IMG][/URL]

Good afternoon.

I request your valuable suggestion for the above cited subject.

I here by uploading the file for your kind notice.

Hey,

I've been trying to divide an equation into matrixes, with not a lot of luck.

Simple example:

A=2b remade into [A]=[2]*[b]

This is a basic overview of the problem, i need it to work with bigger matrixes.

Thank you in advance.

Hi,

Following situation: I have Records with several members. These members in turn have varied expressions assigned to them: some have numbers, one has a Matrix, some have formulae. Example:

q:=Record(l=len,k1=kl/len,R=(a 6x6 Matrix dependent on len and kl/len));

I want to be able to use the limit command on each of the members of q such that each member gets assigned the correct limit of its expression. I.e. I want to write a function limit2 such that

limit2(q,len=0);

yields

Record(l=0,k1=infinity,R=(limit~(the Matrix,len=0))

The trick here is that the members of the Record vary for different Records but I want to write a function limit2 that works for all of these. I can make a list of the members by using exports(q) like this:

exlist:=[exports(q)];

and after some fiddling I found that I can run limit on each member in turn:

for nam in exlist do
  limit~(eval(parse(cat(elm,":-",eval(nam)))),len=0)
end do;

What I have not been able to do is putting the result back into the member of the Record. Usually I would use assign for such a task, but I am unable to get the correct name on the left side that lets me assign to it. These names would of course be q:-l, q:-k1 and q:-R in the above example. I tried the parse(cat(...)) construct above and variations, but in the best case the assignment does not happen, in worse cases I get an error thrown. Never do I get the actual assignment.

Any hint how to do this?

TIA,

M.D.

PS: FWIW, I am doing this on Mape 15.

I am solving a system of ODEs with dsolve(ODES, numeric, method = lsode[adamsfull]) and I noticed that some of the solutions are really small numbers, of the order of 10^-{10} and smaller. Certainly for all intents and purposes I will treat those as zero, but my question is: what flag do I set in dsolve to force Maple stop seeking for a solution when it is so close to zero and set it to 0.0? It seems like a great waste of computational time to try and find the significant digits of the order one number in front of 10^{-10} for any particular solution, at least in my case. So, is there a way to add some option in dsolve such that maple sets that to zero before trying to fully calculate it fully (i.e. all the significant digits) ?? I have looked at abserr and relerr but that does not do the trick. 

IF the question was asked before, forgive me. I have tryed to find an answer within the search here and on the maple help page but was unsuccessful. 

This should be trivial but I am not able to figure out the right syntax to execute it

The pdf is given by :

f_X(x)={ 1/25 *x, 0<=x<5

             2/5 -x/25, 5<=x<10

             0, otherwise

I have tried to use the "CumulativeDistributiveFunction" so far

Hello. I have an inequality and I need to prove or negate if it is true or false. This inequality has 8 variables. I simplify it and try to see if it is ture or false. I tried "test relation" in maple and it seems I can't say it is always true or false. For some values of the variables it is true and for some others its false. Is there a method I can show if this inequlity is hold under some assumptions? I mean I want to keep some variables as constant and prove it up to a point. My inequlity is below. Thank you for the help in advance.

(P[A]*(p-w)/(1-P[A])-c)*H[A]+(w-P[A]*(p-w)/(1-P[A]))*P[A]*H[A]+w[u]*P[B]*(1-P[A])*H[B] < (P[B]*(p-w)/(1-P[B])-c)*H[B]+(w-P[B]*(p-w)/(1-P[B]))*P[B]*H[B]+w[u]*P[A]*(1-P[B])*H[B]

And this is how it looks on maple:

I’ve been having some issues working with large datasets / matrixes in maple 17.02 and 2015. My data consists of a 10^7 x 14 csv file with several lines of header information. Attached is a small sample. The ImportData assistant hangs while importing said file. The javaw process stops responding for a period of time then stops consuming cpu time. I’ve have successfully imported a file of the same format but reduced in size (10^6 x 14) with this same function. So I don’t believe it’s a formatting issue but rather its size.

Are there size limitations to the ImportData function?

The attached maple file has a test case in which the data set (sans header info) is created and exported as a csv file. The export time took longer than I expected (~2 hrs). I then attempted to import the file using two different functions. The ImportMatrix function successfully imported the test case file in approximately 20 minutes, however the ImportData functions seems to fail in the same way as it does importing my actual dataset. I haven’t successfully used the ImportMatrix function on my actual dataset; I’m assuming the header information is the source of the problem.

Are there other methods to import this data?

As stated above, I’m tried both maple 17 and 2015 both 64 bit versions running on an Intel i7 M620 @ 2.67Ghz, 8 GB ram (~ 6 GB avail), sata 2 ssd.

Thank you,

Ron

importtest.mw  Sample.txt

I have to solve a numerical problem and I was wondering how to make maple treat very small numbers as zero. Say I do not care about anything less than 10^-5, so maple should treat all such numbers as zero. How to set this behaviour for the entire session? Thanks!

Hi!

I am trying to solve a large nxl system of coupled differential equations. Maple seems to have trouble even for small n's so I wanted to know if anyone has any suggestions. Take the case of the following system of ODEs for my unknown functions f[0,0](x) and f[1,0](x). 

ODEs:= {diff(f[0, 0](x), x)+2.*f[0, 0](x)/x^5+.5000000000*f[0, 0](x)/x = -15.58845727*sin(.5773502693*x)/x^2+140.2961154*sin(.5773502693*x)/x^4-81.*cos(.5773502693*x)/x^3, diff(f[1, 0](x), x)+6.*f[1, 0](x)/x^5+1.500000000*f[1, 0](x)/x-1.*f[0, 0](x)/x = -15.58845727*sin(.5773502693*x)/x^2+25.98076212*sin(.5773502693*x)*(1/x^4)^(1/4)*exp(1/x^4)*GAMMA(.7500000000, 1/x^4)/x^2+140.2961154*sin(.5773502693*x)/x^4-233.8268591*sin(.5773502693*x)*(1/x^4)^(1/4)*exp(1/x^4)*GAMMA(.7500000000, 1/x^4)/x^4-81.*cos(.5773502693*x)/x^3+135.*cos(.5773502693*x)*(1/x^4)^(1/4)*exp(1/x^4)*GAMMA(.7500000000, 1/x^4)/x^3-20.78460970*sin(.5773502693*x)/x^6+6.000000004*cos(.5773502693*x)/x^5+62.35382908*sin(.5773502693*x)/x^8-36.00000002*cos(.5773502693*x)/x^7, f[0, 0](.1) = 1.503497680, f[1, 0](.1) = -.5011660086}

Following Preben Alsholm's suggestion from my previous thread I am using lsode[adamsfull], since no other method i have tried worked for this problem. I am currently using:

Sollsodefull:=dsolve({ODEs}, numeric, method = lsode[adamsfull])

and it seems to work. I am wondering if there is a way to optimize this, as I will be extending my problem to n and l much larger than order unity numbers, therefore my system will contain about 10^4-10^5 equations. Solving this symple system of 2 equations takes a bit less than a second, but still it takes some time for the processor on my MBP. I am affraid it will be a nightmare for the full problem. Whats the most optimal dsolve option for this kind of problem? Any ideas?

I have also attempted dverk78, rkf45,rosenbrock, lsode(without the adamsfull option), and all failed for this particular system. Errors were:

1. For rkf45: Error, (in f00) cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up

2. For dverk78: Error, (in Soldverk78) cannot evaluate the solution past .1, step size < hmin, problem may be singular or error tolerance may be too small

3. For rosenbrock: Error, (in dsolve/numeric/SC/firststep) unable to evaluate the partial derivatives of f(x,y) for stiff solution

4. For lsode without [adamsfull]: Error, (in Sollsode) an excessive amount of work (greater than mxstep) was done

5. For default method with stiff=true and inplicit=true options: Error, (in dsolve/numeric/SC/firststep) unable to evaluate the partial derivatives of f(x,y) for stiff solution

Dear all,

I want to use the Maple Compiler to improve the performance of some of my codes. To get used to it, I tried doing the examples from the ?Compiler help-page, but everytime I run the compiler, I get the error message:

"Error, (in Compiler:-Compile) compiler exited with nonzero status 1: 

Do some of you know a possible reason for this?

Thank you all.

Download test.mw

I am not aware if is a problem with me or else.

Have some questions about the select command and (possible) big tensorial expressions. I think it would be a simple question to manage, but I still have problems.

TensorEnergiaMomento.mw

Thanks a lot

Is it possible to let maple, given a certain equation of the form f(x,y,z)=0, find a parametric form of the surface/volume enclosed by that function?