Hi Curtis,
First I'd like to say that I admire your open mind and the tolerance you
display here. Maybe I should be a little less zealous as well :-)
But my university pays about 500 k€ each year (550 k$ !) only to be able to
use Matlab and we even have the cheap academic license ! That sometimes
irritates me ...
About Octave : the speed of both Octave and Matlab largely depends on the
Blas and Lapack libraries that sit behind the curtain. If you use a heavily
optimised Blas (like the Atlas stuff) Octave will be ways faster as well.
And ... Blas and Lapack are also Open Source ...
Using Blas and/or Lapack directly from C instead of through Matlab could be
much faster and isn't that difficult although it uses a somewhat archaic
Fortran based calling mechanism.
And another old but very good (C oriented) library for Linear Algebra is
Meschach : very intuitive and probably 5 times faster than Matlab for many
apps :-)
/***************** Meschach example : *********************/
#include <stdio.h>
#include <stdarg.h>
#include <math.h>
// This comes from the Meschach solver library :
#include "matrix.h"
#include "matrix2.h"
int main(int argc,char *argv[])
{
MAT *A;
MAT *LU;
VEC *b,*x;
PERM *pivot;
// reserve space for the matrix equation variables :
A = m_get(3,3);
b = v_get(3);
x = v_get(2);
// Fill the known vector b and matrix A
b->ve[0] = 1; b->ve[1] = 2; b->ve[2] = -1;
A->me[0][0] = 3; A->me[0][1] = 5; A->me[0][2] = 2;
A->me[1][0] = 0; A->me[1][1] = 3; A->me[1][2] = 4;
A->me[2][0] = 1; A->me[2][1] = 6; A->me[2][2] = 4;
// And solve the system A.x = b using the Meschach routines :
LU = m_get(A->m,A->n);
LU = m_copy(A,LU);
pivot = px_get(A->m);
LUfactor(LU,pivot);
x = LUsolve(LU,pivot,b,VNULL);
m_free(LU);
px_free(pivot);
v_output(x);
}
Also Python is definitely worth looking at : Numpy, Scipy , Sympy and
Matplotlib are just as easy to use as Matlab.
Discussion closed ?
Regards,
Kees
On Friday 01 June 2012, Curtis Olson wrote:
> On Fri, Jun 1, 2012 at 3:20 AM, Kees Lemmens
>
> <c.w.j.lemm...@ewi.tudelft.nl>wrote:
> > Ji,
> >
> > Just wondering : why are some of you using an Open Source Flight
> > Simulator only to connect it to one of the most expensive (read least
> > value for money)
> > mathematical software packages in the world ?
> >
> > You could at least consider trying to hookup to Octave (an Open Source
> > Matlab
> > lookalike), Scilab or Numpy/Scipy instead : that would fit the ideas
> > behind Flightgear a lot better ;-)
> >
> > I suggest the people who want to connect to Matlab to try a commercial
> > simulator like MS-FlightSimulator instead ...
>
> To be fair, many people using matlab are students or work for larger
> companies that have purchased this software already. I'm a big open
> source fan, but one matlab script I have here ran about 1/10th the
> speed in octave -- although octave did produce correct results (within
> the margins of floating point rounding variations.) If you are working
> with large data sets or you are working on your code and need to
> iteratively run/test/edit many times, that extra speed may be worth the
> cost of the package -- but everyone's situation is different, and
> everyone is working on different problems with different data. Many
> people (myself usually too) have more time than money.
>
> I used to be more of a software/platform/os advocate than I am now --
> I've come to think that if a person is happy and comfortable and
> productive with the tools they are using, then that is a good thing --
> of course as long as that includes FlightGear. :-) I see no evil in
> purchasing software if it helps you get a task done. Personally I run
> Linux and use open-source tools almost exclusively, but there are times
> when a commercial package does work better or offers some feature that
> an open-source package does not. There are other times when an
> open-source solution works best.
>
> If someone is looking for a tool or a solution to a problem, that's
> definitely the time to suggest open-source alternatives in my view. But
> if someone is settled in and happy, let them work in peace. :-)
>
> Curt.
--
Bye,
Kees Lemmens,
Email : kees.lemmens<at>gmail<dot>com
---------------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
Bye,
Kees Lemmens,
Email : kees.lemmens<at>ipact<dot>nl
-----------------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
C.W.J. Lemmens,
Email: c.w.j.lemm...@tudelft.nl,
Office: +3115-2787224,
NOTICE: to minimize spam I'll trash HTML based email immediately,
so don't send HTML messages if you'd like me to read it !
--
With best regards,
Kees Lemmens,
Email : lemmens<underscore>kees<at>yahoo<dot>co<dot>uk
----------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
With best regards,
Kees Lemmens,
Email : lemmens<underscore>kees<at>yahoo<dot>co<dot>uk
----------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
With best regards,
Kees Lemmens,
Email : lemmens<underscore>kees<at>yahoo<dot>co<dot>uk
----------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
With best regards,
Kees Lemmens,
Email : lemmens<underscore>kees<at>yahoo<dot>co<dot>uk
----------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
With best regards,
Kees Lemmens,
Email : lemmens<underscore>kees<at>yahoo<dot>co<dot>uk
----------------------------------------------------------------
BTW: Ceterum Censeo Microsoftem esse Delendam
--
C.W.J. Lemmens,
Email: c.w.j.lemm...@tudelft.nl,
Office: +3115-2787224,
NOTICE: to minimize spam I'll trash HTML based email immediately,
so don't send HTML messages if you'd like me to read it !
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