Maple 18 Questions and Posts

These are Posts and Questions associated with the product, Maple 18

Hi Maple friends.

If Maple solves an equation and spits out an answer like this,

{x = 4/3+(1/3)*sqrt(7)}, {x = 4/3-(1/3)*sqrt(7)}

how can I get a decimal answer, other than by using my calculator?

Thanks in advance.

Hi everyone

Right now I am working on a command that calculates the molar mass of molecules. Mostly it is working like a charm but in some cases the interpretation of the input goes wrong.
The command converts the input to a string, e.g.:

f:=convert(Ca3(PO4)2, string) = "Ca[3](PO[4])[2]"

f := StringTools:-Remove("[]_*^+-", f) = "Ca3(PO4)2"

 

However, sometimes information such as parentheses is lost (which is understandable considering the fact that maple does not know chemical syntax):

f := convert(NH[3][3]*PO[4], string) = "NH[3][3]*PO[4]"

f := StringTools:-Remove("[]_*^+-", f) = "NH33PO4"

 

In special cases it goes completely nuts (I am aware this is not a real molecule):

f := convert(Al(OH)2(NH3)2, string) = "Al(`#msub(mfenced(mi("OH")),mn("2"))`)(NH[3])[2]"

 

The problem could of course simply be solved by typing the input as a string with no subscripts but is looks much nicer with the correct chemical syntax as input.

Do any of you know a way to translate the input charactor by charactor into a (understandable) string?

 

Thanks in anvance,
Mads 

 



Hello,

Is it possible to install on the same machine both the version 32bits and 64bits ?

For example, for some software (like visio) it is possible to have several version of the softwares.

In fact, it can be useful for me because with 32 bits I can communicate with 32bits softwares and with 64bits I can do quicker some calculations.

Thank you for help.

 

I have an indexed equation that contains serval definite integrals in it. I want maple to evaluate the equation for different indices. But when I set the parameter "N=100" in the code, it takes maple lots of time for the evaluation. I am looking for some tricks to make the code numerically more efficient. I will be so thankful for any opinion and help.
you can find my code below. The code is so simple and just contains few lines. I will appreciate any help.

Numerical_Performance.mw

Thanks in advance.

For two angles a and b, and functions f and g, I have a system of two equations,

diff(a(t),t$2) = f(a(t), b(t), diff(a(t),t), diff(b(t),t)) and diff(b(t),t$2) = g(a(t), b(t), diff(a(t),t), diff(b(t),t)).

The actual equations (i.e. not in terms of f and g) are known but are ommitted because they are very long.

 

I need not the solutions but simply the time t at which a(t) = b(t). While I have inputted the full equations into Maple, I do not know how to ask it to find an expression for t in terms of the constants of the equation.

How would I ask Maple to find this time?

I am sure that with this vector file with embedded components will learn how it works the vector operations. The code is free and can be modified to be improved. Forward engineers.

 

Vectores_con_Components_Embedded.mw     (in spanish)      

 

Lenin Araujo Castillo

I'm used to Mathcad, and I am very new to Maple. Something I cannot figure out right now is how to define multiple elments of a matrix using a function.


Input Data

Define system dimensions as n:=2;

i:=1..n;

j:=1..n;

lambda:=Matrix(n);

Lambda:=Matrix(n);

upsilon:=vector(n); 

Minor side note: I originaly had upsilon defined using the syntax "Vector[row](ncomp)", but this was giving me an 'exponentiation' operation error, so I changed it to what it is now (basically a list/array, which I guess has different type definitions that no longer cause the error?).

lambda[1,2]:=471.0433;

lambda[2,1]:=883.7530;

upsilon[1]:=58.69;

upsilon[2]:=18.07;

The Problem I'm Having

Now I just want to define Lambda using a function to define all elements (like I would in Mathcad).

Lambda[i,j]:= (upsilon[j]/upsilon[i]) * exp (-lambda[i,j]/2853);

which gives me an extremely long error message:

Error, invalid input: exp expects its 1st argument, x, to be of type algebraic, but received Matrix(2, 2, {(1, 1) = -0.3504976272e-3, (1, 2) = -.16509955895845776, (2, 1) = -.30975332953088164, (2, 2) = -0.3504976272e-3}, datatype = float[8]

As far as I can tell (keep in mind that this is my very first Maple project) that it doesn't like lambda as a matrix? But shouldn't it just evaluate to the element? and why is (2,2) and (1,1) giving values, because it should intialize to zero, so exp(0) = 1 in these cases??

I tried to simplify further by just trying

Lambda[i,j]:=(upsilon[j]/upsilon[i]);

but then it just gives me 1, and when I look into Lambda all the elements are now 1 when only the diagnol elements should be 1 (the rest some fractional amount)??

I am at a complete loss. I thought about doing something like For i = 1 to n etc. but then it just looks like coding, which defeats the purpose of trying to make a calculation sheet documenting the procedure...

Any help and/or insights into what I am doing wrong here would be most welcomed :)

P.S. I've just noticed that there is an upload option :/ Wilson_Equation.mw.

 

I have been learning to use the Physics package in Maple 18.  I just updated to the latest version of the Physics package to see if it would fix the problem by my results are the same.

When I take a covariant derivative in spherical coordinates it does not appear to have a scale factor such as g_kk below.  

 A_(j;k)=1/(g_(kk))(partialA_j)/(partialx_k)-Gamma_(jk)^iA_i,

This definition of comes from the Mathworld web site.  I think they have a typo such that it should actually read h_k which is the scale factor instead of g_kk which is the metric.  They are related by h_k^2 = g_kk.

Why doesn't Maple's covariant derivative have the scale factor when I am differentiating in spherical coordinates?

Thanks!

One of my students just showed me the following strange behaviour with Maple 18 (17?) on her Mac computer:

After entering anything at all in math mode, the Enter key has no effect.

After an empty line in math mode the Enter key works fine, and also after anything (including nothing) in text mode.

She has uninstalled and reinstalled Maple several times.

I have absolutely no clue. Do you?

If nobody has a clue, I will be back with more detailed information.

Knud Fjeldsted
Denmark

Hi,

 

I am having trouble solving the PDE. Can anyone shine some light?


``

sys:=-(1/2)*(diff(f(phi, s[1], s[2], w[1]), s[1]))*(s[1]-s[2])*s[1]/(s[2]*w[1])+(1/2)*(diff(f(phi, s[1], s[2], w[1]), s[2]))*(s[1]-s[2])*s[2]/((-1+w[1])*s[1])+diff(f(phi, s[1], s[2], w[1]), w[1]) = 0;

-(1/2)*(diff(f(phi, s[1], s[2], w[1]), s[1]))*(s[1]-s[2])*s[1]/(s[2]*w[1])+(1/2)*(diff(f(phi, s[1], s[2], w[1]), s[2]))*(s[1]-s[2])*s[2]/((-1+w[1])*s[1])+diff(f(phi, s[1], s[2], w[1]), w[1]) = 0

(1)

pdsolve(sys);

 

``


Download 1234.mw

Say the values of i^2 are being calculated from within a procedure,

 

mytest:=proc(n)

local ans;

    ans:=0;

    for i from 1 to n do

   ans:=ans+i^2;

   end do;

   return ans;

end proc;

 

Could I have a (time series) plot of i^2, while the values are being calculated?

The above is a toy example. What I want to archieve is to track a particular intermidiate values while the procedure is running.

 

Thanks,

 

casper

Hi Maple friends.

x(x+y)^4 = y(3*x-y)^2

When I differentiate implicitly by hand, I get:

-5*x^4-4*x^3*y+3*y^2/x^4-6*x*y+3*y^2 (my lecturer also got this solution)

Maple gives the result as: 

(-2*x(x+y)^3*(D(x))(x+y)+3*y(3*x-y)*(D(y))(3*x-y))/(2*x(x+y)^3*(D(x))(x+y)+y(3*x-y)*(D(y))(3*x-y))

Maybe I am doing something wrong in Maple? From the context menu, I choose implicit differentiation, and then select y as the dependent variable. How can I get Maple to give the same solution?

Thanks in advance.

Phil Yasskin (Texas A&M) has prepared a maplet for the Maplets for Calculus proiect. While this maplet works, in Malmem 18 it sometimes does NOT display the plot. We don't see this behavior in Maple 17, The maplet is attached for your convenience, if you are interested in seeing if it works for you.

HorAsymp-KD-ms-PY3.mw

The problem is difficult to describe. Basically, at the end of the problem, users can elect to see a plot of the function with(some) asymptotes. The code creates the plot when the problem is created, and displays this plot in the worksheet. But, when the plot is requested within the mapmlet, it sometimes does not show in the empty plot window.

Any explanations (or followup quesitons) will be greatly appreciated.

Doug

---------------------------------------------------------------------
Douglas B. Meade  <><
Math, USC, Columbia, SC 29208  E-mail: mailto:meade@math.sc.edu
Phone:  (803) 777-6183         URL:    http://www.math.sc.edu

Hi,

I read this thread, but it didnt really help.

test.mw (i noticed an error in the expression pj, now fixed!)

See this file above.

The function needs to be maximized is "loglik", with constraints,

f0>0, sigma>0 and mu is FREE. Only three variables.

 

Using some calculus and by changing variables, I was able to use Gauss–Hermite quadrature, and do some approximation, to get the values:

f0=105.9535

mu=-2.1587

sigma=3.5156

 

I am wondering if Maple can do this straight away. By that, I mean, without doing much further,  how could I get the values? (most efficiently and quickly)

 

Thanks,

 

casper

 

http://www.mapleprimes.com/questions/122813-Is-It-Possible-To-Optimize-This-Kind-Of-Integral

Hi,

This maybe a really simple question, I remember this is doable but couldnt find where the answer is.

Say I write a function to sum up all values in the list,

mysum:=proc(data::list)

return printf("The sum is %3.3f. ", sum(data[i],i=1..numelems(data)));

end proc;

 

and I use it like,

mysum(listA);

mysum(listB);

 

How would I print out a more informative string, like this:

"The sum of listA is %3.3f. "

"The sum of listB is %3.3f. "

 

Use "data", the input, as a string argument.

 

Thanks,

 

casper

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