you can launch the frontend as MathLink child from the kernel.
lnk = LinkLaunch[C:Program FilesWolfram
ResearchMathematica4.0Mathematica.exe -mathlink]
<
> using HTMLSave I want to convert several notebooks to html-files.
> Everything works fine, but now I want to start the HTMLSave command from
> a batch. It is impossible to do this by the standalone Mathematica
> kernel, since HTMLSave needs the front end for this conversion. Does
> anyone know how to start the front end from batch mode to execute one
> single cell?
>
> Thank you very much
> Alexander Dreyer
> --
> / Alexander Dreyer, Dipl.-Math. - Abteilung Adaptive Systeme
> / Fraunhofer Institut fuer Techno- und Wirtschaftsmathematik (ITWM)
> Gottlieb-Daimler-Strasse, Geb. 7^2=49/302 D-67663 Kaiserslautern /
> http://www.itwm.fhg.de Tel.:(0631)205-4472 Fax:(0631)205-4139 /
====
>
> Fernando:
>
> Write a ASCII file (with extesion file.m) with the
> commands you want to run. Then from your prompt
> execute for example the following command:
>
> nice +16 math & file.out&
>
> When finished you will find the output in the file
> file.out
>
> Cesar Guerra
> Fisica - PUCP
[...]
doing it that way doesn't work on my machine. Which shell are you using?
Greeting,
Alexander Dreyer
--
/ Alexander Dreyer, Dipl.-Math. - Abteilung Adaptive Systeme
/ Fraunhofer Institut fuer Techno- und Wirtschaftsmathematik (ITWM)
Gottlieb-Daimler-Strasse, Geb. 7^2=49/302 D-67663 Kaiserslautern /
http://www.itwm.fhg.de Tel.:(0631)205-4472 Fax:(0631)205-4139 /
====
you can't do that. Because Mathematica copy lists very often
and a single copy operation will bring the full data set into your
memory. So you can't make Mathematica think that it is a list.
In one of the Mathematica Programmer books by Roman Maeder is
an implementation of infinite long lists. This coed may
help you to make the MathLink functions for your problem.
Jens
>
>
> I have a perhaps advanced MathLink question. Here's what I want to do:
>
> I want to have an object in Mathematica that Mathematica thinks is a
> list. But in reality, whenever Mathematica wants to get an element of
> the list it calls a MathLink function that retrieves the value.
>
> The idea here is to access a very large dataset (so large that I don't
> want to have to *copy* it to a real Mathematica list) accessable from
> Mathematica using all of the nice list functions (like ListPlot). I can
> write a C program that can randomly access and iterate over the dataset
> quickly, so it would seem to make sense for Mathematica to use my C
> program instead of holding the large dataset in its own memory.
>
> and haven't seen anything about doing something like this. Anyone have
>
> --- Adam
>
> Adam Lyon / Univ. of Rochester Group at CLEO
> Wilson Synchrotron Lab (Cornell University, Ithaca, NY)
====
Table[{a,b,c,1-a-b-c,f[a,b,c,1-a-b-c]},{a,a0,a1,da},{b,b0,b1,db},{c,c0,c1,dc
}]
??
Jens
>
>
> I've got the following problem:
> I have a function that depends on 4 parameters, f(a, b, c, d), whereby
> a+b+c+d=1.
> Now, I would like that Mathematica gives me table with values for the
> parameters and of course the corresponding f(a,b,c,d). Furthermore, I
would
> like to set the step range of the parameters.
> The goal is to have a table like:
>
> a b c d f(a,b,c,d)
> 0.1 0.1 0.1 0.7 0.1324
> 0.1 0.1 0.2 0.6 0.2143
> ....
>
> Thx in advance.
> HAND
> Sven
====
hello , I am intersted in solving the following problem in Mathematica :
-Laplacian[[Psi][x, y]] == 2 , in [CapitalOmega]
[Psi][x, y] = 0 , on [CapitalGamma]
where [CapitalOmega] is the domain , and [CapitalGamma] is the boundary
Lets say that The boundary is a circle with radious = 1 .
Thank you for your help , Doron .
====
In this case, a small excerpt from the file you're trying to read would be
very helpful ....
Attempting to simulate your problem below, shows no problem with under 4.01
...
In[19]:=
test = Table[Random[Real, {-1, 1}], {343}];
test = Partition[test, 7] / 100000.;
Export[test01.dat, test];
testi = Import[test01.dat, Table];
testi == test
Out[23]=True
> Also, later when it works I need to plot the columns, something like
> Plot[data(2,*)]
> you know, plot the second column.
> The code doesn't work, mathematica doesn't take arrays like
> that, not sure why.
Both the syntax and the command are incorrect ...
For the example above,
In[31]:= Dimensions[test]
Out[31]= {49,7}
So ...
In[32]:= Dimensions[#]& /@ {test[[2]], Flatten[ColumnTake[test, {2}]]}
Out[32]= {{7},{49}}
So to plot the second column, try
sndcol = Flatten[ColumnTake[test, {2}]];
(* or Transpose[test][[2]] *)
ListPlot[sndcol];
Or the second row ....
sndrow = test[[2]];
ListPlot[sndrow];
For your other problems, I can only suggest a closer inspection of the
Bible.
Dave.
--------------------------------------------------------
Dr. David Annetts EM Modelling Analyst
Tel: (+612) 9490 5416 CSIRO DEM, North Ryde
Fax: (+612) 9490 5467 David.Annetts@csiro.au
Include usual_disclaimers
--------------------------------------------------------
====
whats wrong with:
Unprotect[Derivative]
Derivative[n_Integer][f_ + g_] := Derivative[n][f] + Derivative[n][g]
Protect[Derivative]
??
Jens
>
> Dear MathGroup,
>
> I would be interested in any comments on this little piece of Mathematica
> and mathematics.
>
> If f and g are functions and a and b are constants, we usually use the
rule
>
> (a f + b g)[t] == a f[t] + b g[t]
>
> What about
>
> (a f + b g)'[t] == a f'[t] + b g'[t] ?
>
> What is the easiest method to get Mathematica to make this
simplification?
> Mathematica won't simplify the above expression (of course, how does it
know
> that f and g are functions?), but it won't simplify the following either.
>
> (Cos + Sin)'[t] or even
>
> (Cos[#] & + (Sin[#] &))'[t]
>
> Nor does Through seem to work.
>
> It seems that the way to simplify (a f + b g)'[t] is to actually write
>
> (Function[t, a Function[t, f[t]][t] + b Function[t, g[t]][t]])'[t]
> a f'[t] + b g'[t]
>
> will convert a linear derivative expression to the functional form. You
have
> to give it a list of symbols which will be regarded as functions.
>
> DerivativeBreakout[functions_List][expr_] :=
> Module[{temp},
> temp =
> expr //. Derivative[args__][a_ + b_] : Derivative[args][Function[t, a[t] + b[t]]];
> temp //.
> Derivative[args__][
> a_?(FreeQ[#, Alternatives @@ functions] &) f_?(MemberQ[
> functions, #] &)] : Derivative[args][Function[t, a f[t]]]
> ]
>
> (a f + b g)'[t]// DerivativeBreakout[{f, g}]
> a f'[t] + b g'[t]
>
> (Cos + Sin)'[t] // DerivativeBreakout[{Cos, Sin}]
> Cos[t] - Sin[t]
>
> Is there a better method for doing this?
>
> David Park
> djmp@earthlink.net
> http://home.earthlink.net/~djmp/
====
Mathematica is presently having problems starting up on my machine.
The splash screen comes up, but then it just hangs on initializing
notebook defaults. I thought that some files may have gotten
corrupted in the installation due to recent system crashes,
so I reinstalled it, but this did not get rid of the problem.
Anyone out there have the same problem - and if you know how to
fix it I would be very grateful..!
====
I have a little problem in integral transform definition.
I want to define the following integral transform depending on a parameter
n
g(y,n)=integral[K(n,y,x)f(x)dx] (a<=x<=b)
where, for example, Kern(n,y,x)=sin(n x y) in (0-2Pi) square.
So a I build the function
MyTransf[n_, func_, y_] := Integrate[Kern[n, y, x] func[x],
{x, 0, 2 Pi}] // FullSimplify
and try it
test1[x_]:=Cos[5 x]
g[t_, m_] := Evaluate[MyTransf[m, test1, t]]
m=4; g[z,m]
(out) 8 z (Sin[4 pi z])^2/(16 z2-25)
So far so good. Now I want to apply MyTransf again to this result, changing
the parameter.
I have to define an intermediate function without parameters and sigle
variable
test2[x_]:=g[x,4]
and then
m=2;
Evaluate[MyTransf[m, test2, t]]
(out) 1/16((-CosIntegral[.................etc.........
My problem is to avoid the definition of the intermediate function.
How can define MyTrans so that I can write simply
MyTransf[n, func[m1,m2,...,x], y]
i.e a definition where I can use funcions with explicited parameter(s)
m1,m2..,
the name of the input variable (here x) and the name of the output variable
(here y)?
Having this definition, I could write (my final wish)
MyTransf[n2, MyTransf[n1, f1[m1,x], y], z]
and then find for each n1 the vale of n2 (if exist) for which this double
transform
correspond to other transform, i.e. I want to test if these transforms act
like a group.
Please,help me!
Rob.
Roberto Brambilla
CESI
Via Rubattino 54
20134 Milano
tel +39.02.2125.5875
fax +39.02.2125.5492
rlbrambilla@cesi.it
====
can you be so kind and post correct Mathematica syntax if you write
mathematics ? You can't avoid to use function but
you can define pure functions on fly with:
Kern[n_, y_, x_] = Sin[n x y]
MyTransf[n_, func_, y_] :=
Integrate[Kern[n, y, x] func[x], {x, 0, 2 Pi}] // FullSimplify
g[t_, m_] := MyTransf[m, Cos[5*#] &, t]
m = 4; g[z, m]
m = 2;
MyTransf[m, g[#, 4] &, t]
Jens
>
>
> I have a little problem in integral transform definition.
> I want to define the following integral transform depending on a parameter
n
>
> g(y,n)=integral[K(n,y,x)f(x)dx] (a<=x<=b)
>
> where, for example, Kern(n,y,x)=sin(n x y) in (0-2Pi) square.
>
> So a I build the function
>
> MyTransf[n_, func_, y_] := Integrate[Kern[n, y, x] func[x],
> {x, 0, 2 Pi}] // FullSimplify
>
> and try it
>
> test1[x_]:=Cos[5 x]
> g[t_, m_] := Evaluate[MyTransf[m, test1, t]]
>
> m=4; g[z,m]
> (out) 8 z (Sin[4 pi z])^2/(16 z2-25)
>
> So far so good. Now I want to apply MyTransf again to this result,
changing
> the parameter.
> I have to define an intermediate function without parameters and sigle
> variable
>
> test2[x_]:=g[x,4]
>
> and then
>
> m=2;
> Evaluate[MyTransf[m, test2, t]]
> (out) 1/16((-CosIntegral[.................etc.........
>
>
> My problem is to avoid the definition of the intermediate function.
> How can define MyTrans so that I can write simply
>
> MyTransf[n, func[m1,m2,...,x], y]
>
> i.e a definition where I can use funcions with explicited parameter(s)
> m1,m2..,
> the name of the input variable (here x) and the name of the output
variable
> (here y)?
> Having this definition, I could write (my final wish)
>
> MyTransf[n2, MyTransf[n1, f1[m1,x], y], z]
>
> and then find for each n1 the vale of n2 (if exist) for which this double
> transform
> correspond to other transform, i.e. I want to test if these transforms
act
> like a group.
> Please,help me!
> Rob.
>
> Roberto Brambilla
> CESI
> Via Rubattino 54
> 20134 Milano
> tel +39.02.2125.5875
> fax +39.02.2125.5492
> rlbrambilla@cesi.it
====
hi,
Is there a nice closed form solution to the inverse of a Toeplitz matrix
??
====
and the shell is:
gnome emualtion terminal 1.2.4
I do it on my computer and it works fine:
nice -16 math& file.out&
Cesar Guerra
Fisica - PUCP
> >
> > Fernando:
> >
> > Write a ASCII file (with extesion file.m) with the
> > commands you want to run. Then from your prompt
> > execute for example the following command:
> >
> > nice +16 math & file.out&
> >
> > When finished you will find the output in the file
> > file.out
> >
> > Cesar Guerra
> > Fisica - PUCP
> [...]
>
> doing it that way doesn't work on my machine. Which
> shell are you using?
>
> Greeting,
> Alexander Dreyer
>
> --
> / Alexander Dreyer, Dipl.-Math. - Abteilung
> Adaptive Systeme
> / Fraunhofer Institut fuer Techno- und
> Wirtschaftsmathematik (ITWM)
> Gottlieb-Daimler-Strasse, Geb. 7^2=49/302
> D-67663 Kaiserslautern /
> http://www.itwm.fhg.de Tel.:(0631)205-4472
> Fax:(0631)205-4139 /
>
__________________________________________________
Do You Yahoo!?
Yahoo! Sports - sign up for Fantasy Baseball
http://sports.yahoo.com
====
>
> > Fernando:
> > Write a ASCII file (with extesion file.m) with the
> > commands you want to run. Then from your prompt
> > execute for example the following command:
> > nice +16 math & file.out&
> >
[...]
I misunderstood '' as 'replace by your filename',
'<' and '>' are - of course - the redirection commands.
nice +16 math < file.m >& file.out&
works fine now.
Yours,
Alexander Dreyer
--
/ Alexander Dreyer, Dipl.-Math. - Abteilung Adaptive Systeme
/ Fraunhofer Institut fuer Techno- und Wirtschaftsmathematik (ITWM)
Gottlieb-Daimler-Strasse, Geb. 7^2=49/302 D-67663 Kaiserslautern /
http://www.itwm.fhg.de Tel.:(0631)205-4472 Fax:(0631)205-4139 /
====
I'm trying to plot this function
f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
{a, b} = {-1, 1.5}
Plot[f, {x, a, b}]
and I keep getting an error that says f is not a machine-size real number
at
x = -1. Any help would be appreciated.
====
function calls are written with [] in Mathematica and
only
f[x_] := 1 - (Cos[[ExponentialE]^(3x/4)])
is correct.
Second functions should have *arguments* f is a symbol, f[x] is
a function call, so, f[x] will work:
Plot[f[x], {x, a, b}]
Since Plot has the attribut HoldAll you should use
Plot[Evaluate[f[x], {x, a, b}]]
Jens
>
> I'm trying to plot this function
>
> f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
> {a, b} = {-1, 1.5}
> Plot[f, {x, a, b}]
>
> and I keep getting an error that says f is not a machine-size real number
at
> x = -1. Any help would be appreciated.
====
Mike,
Functions in Mathematica put there arguments in square brackets, not round
brackets. Each type of bracket in Mathematica has a specific meaning. Then,
you have to use f[x] and not just f in the Plot statement.
f[x_] := 1 - Cos[E^(3x/4)]
{a, b} = {-1, 1.5};
Plot[f[x], {x, a, b}];
David Park
djmp@earthlink.net
http://home.earthlink.net/~djmp/
> I'm trying to plot this function
f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
> {a, b} = {-1, 1.5}
> Plot[f, {x, a, b}]
and I keep getting an error that says f is not a machine-size
> real number at
> x = -1. Any help would be appreciated.
====
First, cosine must be written as Cos[...], not Cos(...).
Second, you want to plot f[x], not f.
> I'm trying to plot this function
f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
> {a, b} = {-1, 1.5}
> Plot[f, {x, a, b}]
and I keep getting an error that says f is not a machine-size real number
at
> x = -1. Any help would be appreciated.
====
Your question deals with the problem of defining correctly the value of
such
integral of a function taking on infinite value. The proper way is to use
the so called Cauchy principal value being defined (in your case) as:
limit of Integral[Sec[x],{x,eps,Pi-eps}] when eps-->0
Such limit is called the Cauchy principal value (noted vp) and does
converge
to zero in your case.
Have a look to PrincipalValue in the on-line help.
Philippe Dumas
99, route du polygone
03 88 84 67 80
67100 Strasbourg
----- Original Message -----
> integral to converge. By that definition, Maple is right. But does
> that make sense? The second improper integral is just the negative of
> the first, and they exactly cancel out for the antiderivative
> ln(abs(sec(t) + tan(t)) at any t close to pi/2. Why don't they exactly
> offset each other in the limit, as t goes to pi/2, and yield 0? Why
> shouldn't the integral be so defined, instead of the textbook
> requirement that the improper integrals must separately converge.
====
I have no idea about gcc, but I once had a similar problem in a
completely different context. Since no one else gave you a
technical hint, I'll try it giving you some technical background
on compilers, although I am not sure, if it really helps you.
AFAIK MathLink does not work with GCC. Get the free Borland C/C++ 5.5
>compiler if you like an command line.
Jens
>
>>
>> I am feeling very depressed after I'd spent a full day with MathLink and
>> having had no success. Please help.
>>
>> I use windows 2000 with Mathematica 4.0.
>> I installed the free gcc compiler MinGW.
>> Before moving on a real problem, I tough trying out a simple exercise
would
>> be a wise idea. I copied mathlink.h into /include and mprep into /bin.
Then
>> I tried to compile the addtwo.c (with .tm) from Todd Gayley's tutorial
to
>> MathLink like this:
>>
>> mprep addtwo.tm -o add.c
>> gcc -o add add.c (this should make an executable out of a source, with
>> source being preprocessed template file, if I understand this correctly)
>>
>> Then, ugly thing went over the screen, many of them, all like the two
below:
>>
>> C:DOCUME~1bonaroLOCALS~1TempccuYaaaa.o(.text+0x18e):add.c:
undefined
>> reference to `GetStockObject@4'
It seems to me, that your compiler tries to reference GetStockObject
(probably, it would be written this way on the C level, probably
through macro expansion).
Different compilers use different naming conventions. Some put one or
two underscores after every external symbol name (i.e. f() will
reference an external symbol f_ or f__, some put an @ after it
instead of the underscore, others additionally put the alignment class
or the number of arguments after the @ or they code other compiler
specific things. Other compilers do the same thing by prepending each
name in this manner. The reason is, that some compilers support
different calling conventions, i.e. register based versus stack based.
Before you can use compilation, linkage and debugging tools together
with foreign libraries, you have to check very carefully, if the calling
conventions completely matches. Some compilers have command line or
pragma controllable features, which can influence the code generation,
i.e. they manage different calling conventions and maybe even the way,
how external references are made.
Unfortunately I don't know gcc. You have to look up the documentation
to see, if you can manage it, co generate output, which is compatible
to the mathlink library object code.
If you have found out about it, others in this group might be happy,
to know about your findings.
>> C:DOCUME~1bonaroLOCALS~1TempccuYaaaa.o(.text+0x2ae):add.c:
undefined
>> reference to `MLGetInteger@8'
>>
>> (C:DOCUME~... is my temp dir)
>>
>> I tried various other approaches, but nothing worked. Nothing!
>>
>> Thank You for Your help,
>>
>> Borut Levart
The easiest way, however is to use compilation tools, which are compatible
with the supplied libraries, as Jens said.
====
MathML Conference: Demo and Poster Submission Deadline
=====================
MathML 2002
MathML and Math on the Web
International Conference
=====================
Chicago, Illinois
June 28-30, 2002
The MathML conference provides a forum to present and discuss
current research and applications, with major emphasis on MathML
and technologies that ease the use of mathematical and
scientific content on the web. It is the aim of this conference
to bring together those people involved in creating the future
of mathematics on the web.
The conference embraces all areas of MathML technologies,
including authoring, rendering, content management,
collaboration, searching, archiving, and conversion. Of interest
is work involving courseware or other technologies, such as XML,
XSLT, web services, typesetting, and computer algebra, provided
it relates principally to web-based mathematical communication.
The conference format includes invited speakers, tutorials,
contributed papers, posters, and software demonstrations.
Participation is sought in all areas.
Posters
======
Poster sessions will allow for presentation of new developments
and works in progress. Posters to be considered for presentation
at the conference should be submitted in the form of abstracts
of one to four pages by Friday, March 15, 2002. The program
committee will give notification of acceptance by Friday, March 29.
Demos
=====
A special session will be devoted to live software
demonstrations. To propose a software demonstration, describe
the main aspects of the package, emphasizing its unique or novel
aspects, in two to five pages (including any screenshots) by
Friday, March 15, 2002. The program committee will give
notification of acceptance by Friday, March 29.
Submission and Notification
===================
All submissions must be received by the dates specified.
submitting authors. The preferred method for submission is via
the web at:
http://www.mathmlconference.org/2002/submissions
Important Dates
===========
March 11 . . . Notification of acceptance for papers and panels
March 15 . . . Poster abstracts and demo proposals due
March 29 . . . Notification of acceptance for posters and demos
May 17 . . . Last day for early registration
June 28-30 . . . MathML 2002 conference
July 26 . . . Deadline for full papers for JSC special issue
General inquiries about the conference should be forwarded to
info@mathmlconference.org. Additional conference details and
submission guidelines are available at:
http://www.mathmlconference.org
Organizing Committee
===============
Angel Diaz, IBM Research
Patrick Ion, Mathematical Reviews
Neil Soiffer, Wolfram Research, Inc.
Program Committee
==============
Stephen Watt, The University of Western Ontario (Program Committee Chair)
Laurent Bernardin, Waterloo Maple Inc.
Stephen Buswell, Stilo Technology
David Carlisle, The Numerical Algorithms Group Ltd
Gaston Gonnet, ETH Zurich
Alan Harvey, Cambridge University Press
Michael Kohlhase, Saarland University
Bruce Miller, National Institute of Standards and Technology
Vincent Quint, World Wide Web Consortium
Dana Scott, Carnegie Mellon University
Eric Weisstein, Wolfram Research, Inc.
Wolfram Research, Inc.
Sponsored by:
Waterloo Maple Inc.
Design Science, Inc.
American Mathematical Society
World Wide Web Consortium
====
I think your first problem is addressed in the following FAQ
http://support.wolfram.com/mathematica/kernel/files/fortran.html
which describes how to set up Mathematica 4.0 to accept the exponential
notation
with Import. I often use a completely different method namely
data = ReadList[datafile.dat, Number, RecordLists->True];
which is left over from the pre version 4.0 days which didn't have an
Import[]
command.
To suppress output in Mathematica end a command with a semicolon (as in the
above
command). This will keep Mathematica from printing the entire file.
Finally, to plot your data, you have to use Mathematica syntax not Matlab.
To plot
a list, you need to use the ListPlot[] command (Plot[] plots function
directly).
The argument of ListPlot[] can be in any of several forms, a single list
will be
treated as y-values with x-values assumed to be the list {1, 2, 3, ..., n}.
You
can specify the y and x-values by using a list of {x, y} pairs like
ListPlot[{{x1,
y1}, {x2, y2}, ... {xn, yn}}]. Hope this helps.
Tim Stiles
I have this output file of floating point data from a C program.
> It is all printed in 1.435664334e-013 notation, 7 columns in total.
When I import with:
> data=Import[datafile.dat,Table]
> it doesn't understand the exponential notation.
> It's printing the whole file (huge file by the way) below the command and
> only a handfull of the floats seem to be understood correctly as
1.333^10-13.
> If I print the numbers as 0.00000001234 then mathematica understands,
> but this is not ideal, obviously.
Also, later when it works I need to plot the columns, something like
> Plot[data(2,*)]
> you know, plot the second column.
> The code doesn't work, mathematica doesn't take arrays like that, not sure
why.
I'm very confused about why mathematica have both lists, arrays and
matrices,
> I don't know what to work with in this case.
Is it possible to declare a datatype like in C++ ?
> I like to know what I'm working with, call it force of habbit ;)
Sune.
====
By using the special command of the book Optimization methods with
Mathematica applications (Ashar Bhatti) GraphicalSolution, I get the
following message, the graph is represented but the contourlines are not
represented, so that the graphical solution of the problem is in fact not
possible. does anyone know or has an idea what could have gone wrong here ?
graphics::gprim:
<<63>>[.ContourGraphics.,DisplayFunction->Identity]
was encountered where a Graphics primitive or directive was expected
====
students from south america. Due to our final work,
certain coupled non-linear ODE systems have appear,
and we don't have any idea about how to resolve it, in
spite we attempt to. For our purposes, we would need
analytical solutions -if there exist- for the
following systems,
dx/dt = ax^2 + by^2
dx/dt = cx^2
dx/dt = axy + by^2
dy/dt = cxy + dx^2
Where a, b, c and d are known constants paremeters of
the problem. We would be very grateful if you can help
us with this matter. We were able to fit numerically
the solutions for both systems, in a relatively wide
range of values, but we did not find anything aboout
the analytical solutions for none of the systems. In
brief words, for our work we would need the explicit
expressions for x(t) and y(t), if they are known, of
course. If you can help us, please contact us at,
estudfis@yahoo.com.au
We are very grateful, since this moment.
Sincerely,
Javier Krshpa Sánchez and Héctor Rivera Firpo
Montevideo, Uruguay.
http://movies.yahoo.com.au - Yahoo! Movies
- Vote for your nominees in our online Oscars pool.
====
Try laplace transforms. You will have to express them in terms of
convolutions though.
based on the equations i derive the following:
cx^2=ax^2+bx^2 which means c=a+b; (assuming x is a continuos
function)
from there im not too sure. ill take a look at it later
> students from south america. Due to our final work,
> certain coupled non-linear ODE systems have appear,
> and we don't have any idea about how to resolve it, in
> spite we attempt to. For our purposes, we would need
> analytical solutions -if there exist- for the
> following systems,
dx/dt = ax^2 + by^2
dx/dt = cx^2
dx/dt = axy + by^2
> dy/dt = cxy + dx^2
Where a, b, c and d are known constants paremeters of
> the problem. We would be very grateful if you can help
> us with this matter. We were able to fit numerically
> the solutions for both systems, in a relatively wide
> range of values, but we did not find anything aboout
> the analytical solutions for none of the systems. In
> brief words, for our work we would need the explicit
> expressions for x(t) and y(t), if they are known, of
> course. If you can help us, please contact us at,
estudfis@yahoo.com.au
We are very grateful, since this moment.
> Sincerely,
Javier Krshpa Sánchez and Héctor Rivera Firpo
Montevideo, Uruguay.
http://movies.yahoo.com.au - Yahoo! Movies
> - Vote for your nominees in our online Oscars pool.
====
My system has been doing this also.
I'm using:
Windows 98SE / ME
MathLink for Excel 2.1
Mathematica 4.0.1
John C. Erb
-----Original Message-----
select-copy-MathematicaPaste, then it comes through fine. Switching back
to Standard Form, the comes back.
Has anybody found a fix other than converting to Input Form before
copy-paste?
Chris
====
>
> I hope someone can explain this.
>
> A characteristic of a truly random behavior is that events tend to
> cluster.
> E.g. a molecular collision is more likely to occur just after the most
> recent collision.
> or, in a bit stream, a bit error is more likely to occur just after the
> most recent error if the errors are generated by random noise.
> I simulated this with a generated vector with ones and zeroes with a
> given probability using Random and RandomSeed in Mathematica 3.01. and I
> found something peculiar with the random generation in Mathemathica,
>
> Just run these lines and see for yourself:
>
> SeedRandom[1111111 ] (*change this number to get another random
> sequence*)
>
> vec1=Table[Random[Real,{0,1000}],{10^6}]; (*reduce this
> vector length if you get memory problem*)
> vec2=Map[If[#<44,1,0]&,vec1]; (*threshhold for
> ones*)
> ones=Flatten[Position[vec2,1]]; (*vector of index
> positions for ones *)
> Length[ones]/10.^6 (*check for the
> average of ones*)
> plotvec=Map[Length,Split[Sort[Drop[ones-RotateRight[ones,1],1]]]];
> (*subtracts ones[[i]]-ones[[i+1]]*)
>
> ListPlot[Log[plotvec],PlotRange->All]
>
> It is the plot that seems a bit strange to me, I get the expected
> decreasing exponential behavior in
> the probability of the interval length between ones.
>
> But, (this is the question) in all different simulations I have made
> with different RandomSeed[], average
> of ones, different vector length, the interval of 24 have a lower
> frequency than expected.
>
> If this behavior persists when you test, what is the reason?
> If not, why do I get it, I have tried it on two computers.
>
> hehe.. if you reverse 24 you get 42???
> Peter W
http://library.wolfram.com/mathgroup/archive/2000/May/msg00088.html
In that case as well something bad happened in the 24th bin which was
(as in your case) reliably under where it should have been.
The upshot is that this appears to be a hazard of subtract-with-borrow
based random generators, which is what is used to generate random
machine doubles. This defect does not appear to afflict the cellular
automaton generator used to form random integers smaller than 2^30.
Hence to ellude it in your example you might do as below.
SeedRandom[1111111];
vec1 = Table[Random[Integer,1000],{10^6}]; (* generate integer instead
of real *)
vec2 = Map[If[#<=44,1,0]&, vec1];
ones = Flatten[Position[vec2,1]];
Length[ones]/10.^6
plotvec = Map[Length, Split[Sort[Drop[ones-RotateRight[ones,1],1]]]];
ListPlot[Log[plotvec], PlotRange->All]
For further information, more general workarounds, etc. I defer to my
5/00 post at the URL above.
By the way, I don't think clustering is equivalent to a bit error is
more likely to occur just after the most recent error if the errors are
generated by random noise.
Daniel Lichtblau
Wolfram Research
====
I can't seem to get a Plot working. I have all this typed in the notebook:
Clear[a, b, f]
f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
{a, b} = {-1, 1.5}
Plot [f, {x, a, b}]
I keep getting an error saying f is not a machine-size real number at x
====
>
> I can't seem to get a Plot working. I have all this typed in the
notebook:
>
> Clear[a, b, f]
> f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
> {a, b} = {-1, 1.5}
> Plot [f, {x, a, b}]
>
> I keep getting an error saying f is not a machine-size real number at x
here you go:
Clear[a, b, f]
f[x_] := 1 - (Cos[[ExponentialE]^(3x/4)])
{a, b} = {-1, 1.5}
Plot[f[x], {x, a, b}]
====
I know what you want to do with the line {a,b}={-1,1.5} but this assignment
doesn't work. Write your borders directly into your Plot command.
Also, if you define a function like
f[x_]=1-x
for example, this expression is a replacement rule. The blank _ acts like a
placeholder for something (a pattern). With x_ you can assign this
something the name x. So you can use that something again on the right
hand side of that definition. Two examples
1. You define an assignment like
g[x_,t_]=x+t
2. Now Mathematica will evaluate like this
g[2,6] will evaluate to 2+6 will evaluate to 8
or
g[a,t^2+4] will evaluate to a+4+t^2
You see the way it is done?
So if you define a function with f[x_]=bla bla
and you try to call it in your Plot with Plot[f,{x,a,b}] it won't work,
because an expression f doesn't match the pattern f[x_] so Mathematica
won't
apply that replacement rule on f. You must plot with
Plot[f[x],{x,1,2}] that will do. You don't even have to use the x you can
also write Plot[f[mike],{mike,1,2}].
OK?
Oli
> I can't seem to get a Plot working. I have all this typed in the
notebook:
Clear[a, b, f]
> f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
> {a, b} = {-1, 1.5}
> Plot [f, {x, a, b}]
I keep getting an error saying f is not a machine-size real number at x
====
>I can't seem to get a Plot working. I have all this typed in the
notebook:
Clear[a, b, f]
>f[x_] := 1 - (Cos([ExponentialE]^(3x/4)))
>{a, b} = {-1, 1.5}
>Plot [f, {x, a, b}]
I keep getting an error saying f is not a machine-size real number at x
>= -1.
Clear[a, b, f];
f[x_] := 1 - Cos[E^(3*x/4)];
{a, b} = {-1, 1.5};
Plot [f[x], {x, a, b}];
Bob Hanlon
Chantilly, VA USA
====
Some of your parentheses are incorrect: [] is for functions, () is for
grouping, {} is for lists. Other than that, I guess you should write f[x]
instead of just f in your Plot command:
In[1]:=
Clear[a, b, f];
f[x_] := 1 - Cos[E^((3*x)/4)];
{a, b} = {-1, 1.5};
c = Plot[f[x], {x, a, b}];
works all right.
Tomas Garza
Mexico City
----- Original Message -----
> I keep getting an error saying f is not a machine-size real number at x
====
I would like to know that where can I download some books for mathematica,
I'm very interested in this software. It's a really good tool for me.
====
books can be found in a book store. Typical the authors
wish to have some money and the publisher too.
Jens
>
> I would like to know that where can I download some books for
mathematica,
> I'm very interested in this software. It's a really good tool for me.
====
As far as I know, there are no Mathematica books for downloading (I mean,
for free). I'm afraid you'll have to buy. In the Wolfram website you'll
find
literally hundreds of them.
Tomas Garza
Mexico City
----- Original Message -----
Harvard Square Station