**Levenberg-Marquardt algorithm**In the Optimization toolbox help on the L-M method (http://www.mathworks.com/help/toolbox/optim/ug/brnoybu.html#f204)
it mentions that the "ScaleProblem" option can be used to improve the performance of a poorly scaled non-linear least squares problem by multiplying the Hessian by the lambda parameter.
Basically, I am wondering how this helps exactly. Is it a type of matrix normalization?
Any reference material which described the LM method from an engineering stand point would be greatly appreciated.
Thank you!
"LU " <g21u5@unb.removethis.ca> wrote in mes...

**Levenberg Marquardt algorithm**Hello,
I am wroking on a problem that requires me to use the levenberg
marquardt algorithm.
I am not a physics major and have never herd of any curve minimization
/ levemberg in my life before this day.
The probelem goes like this:
I have a set of points.
x - axis : Energy
y - axis : log of sensitivity
this gives me the initial curve and i make an initial guess.
i have a function f
Yt = ( ( sqr + 1) * ((1 + exp(alpha*(initialGuess - omega -
(energy))))) );
f = log(ys*(1/Yt));
This gives me another set of points based on my initial guess.
I have to minimize it.
But I have no clue of...

**bounds with levenberg-marquardt algorithm**I posted a similar question last week. I am trying to fit mass fractions using lsqcurvefit using the Levenberg-Marquardt algorithm. Since these are mass fractions, I need the values of these fi between 0 and 1, and the sum of the fi to equal 1. I have tried saying:
if sum(f) < 1
fi = [f(1) f(2) f(3) f(4) 1-sum(f)]
else
fi = [f(1) f(2) f(3) f(4) 0];
end
for n = 1:length(fi)
if fi(n) < 0
fi(n) = 0
end
end
Often, fi(n) values turn out negative, specifically, fi(5), since sum(f) > 1.
Is there a better approach to constrain these parameters (i.e., each individual mas...

**Levenberg-Marquardt algorithm #3**Hi
Does anyone know if the Levenberg-Marquardt Method uses any regularization process?
"Mar" wrote in message <l6o19g$a63$1@newscl01ah.mathworks.com>...
> Hi
>
> Does anyone know if the Levenberg-Marquardt Method uses any regularization process?
i dont think so... usually it is mentioned when a solver uses scaling (i assume you mean that). but pls note that more than one procedure use levenberg, so maybe you can be more specific. in lsqnonlin and fsolce you can scale the problem with the jacobian (see the options
...

**Modify Levenberg Marquardt algorithm**Dear All,
Could anyone kindly let me know if it is possible to modify the levenbergmarquardt.m file so that the values of the parameters being optimized can be printed to the console and modified based on a given condition during optimization? I only tried endlessly to do so via the lsqnonlin routine but to no avail.
Besides, I also wanted to find out if a complex model such as
F(x,Theta)= theta3*exp(-theta1x2) + theta4*exp(-theta2*x3) would converge for all possible randomly chosen inital conditions? I also generated the values of the x matrix using random numbers.
Any help will be gre...

**Levenberg Marquardt algorithm speed up**Hi together,
I have a code called 'lma.m' that is used to fit a curve into data with the Levenberg-Marquardt algorithm. This code should be able to analyse a Peak from a Gamma spectrum and ist doing this Job quite well. The only Problem is the Speed or Performance. Analysing one Peak takes about 40-70 sec. Unfortunately this is not acceptable for some students to use the program and learn with it. The 'Run and time' analysis in Matlab 2014a says that most of the time is spent because of the symbolic class 'sym'. Has anyone an idea how this code could be improved?
...

**SWEngr-AVP-Algorithm,2-5yrExp.in design & Development of Audio Algorithm #2**
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**Re: Levenberg**In my previous post, I did not take into account the problem of
constraints on the parameters. The ORTHOREG procedure does not
allow one to impose parameter constraints. However, the REG
procedure allows one to RESTRICT the values of parameters.
From the description provided to this point, I believe that
the REG procedure with a RESTRICT statement is all that is
necessary to fit the model specified.
Dale
---------------------------------------
Dale McLerran
Fred Hutchinson Cancer Research Center
mailto: dmclerra@NO_SPAMfhcrc.org
Ph: (206) 667-2926
Fax: (206) 667-5977
---------------------...

**Fitting an equation to data using the Levenberg-Marquardt algorithm, with boundary constraints**Hi everyone.
I am using lsqcurvefit to fit a signalequation to some data. I am using the=
Levenberg-Marqaurdt algorithm but would really like to put some boundary c=
onstraints on the output. The most important constraint is that all the out=
put parameters are positive but I would like to constrain the values to cer=
tain ranges.=20
lsqcurvefit does not accept boundary constraints for the Levenberg-Marquard=
t algorithm, so do any of you have an idea how I can cheat lsqcurvefit to a=
ccept boundary conditions indirectly somehow or (even better): do any of yo=
u know of another i...

**linspace(2,2,2) returns [2 2] ??**May be the help for linspace should change?
It says:
"LINSPACE(X1, X2, N) generates N points between X1 and X2."
Notice, it says BETWEEN.
But when I ask for 2 points, between 2 and 2:
----------------
EDU>> linspace(2,2,2)
ans =
2 2
---------------
May be mathematically this is ok? i.e. there are infinite points between
the point and itself? (on the real line), but from programming point of
view, it is confusing. no?
--Nasser
Maybe it should say "generates N points between X1 and X2, inclusive."
What did you expect to...

**2 * 2 * 2 * 2 or pow(2, 4)?**Hi ,
I hope this isn't too trivial to ask, but I'm evaluating a polynomial
that involve lots of terms like x^2y^2z^3, and although I can use the
power function pow(a, b), I wonder if just writing x*x*y*y*z*z*z for
example wouldn't be more efficient than pow(x, 2)*pow(y, 2)*pow(z,3).
Or is it all the same?
Thanks,
- Olumide
Olumide wrote:
> I hope this isn't too trivial to ask, but I'm evaluating a polynomial
> that involve lots of terms like x^2y^2z^3, and although I can use the
> power function pow(a, b), I wonder if just writing x*x*y*y*z*z*z for
> exam...

**2**2**2**2**2 wrong? Bug?**In Python 2.5 on intel, the statement
2**2**2**2**2
evaluates to
>>> 2**2**2**2**2
20035299304068464649790723515602557504478254755697514192650169737108940595563114
53089506130880933348101038234342907263181822949382118812668869506364761547029165
04187191635158796634721944293092798208430910485599057015931895963952486337236720
30029169695921561087649488892540908059114570376752085002066715637023661263597471
44807111774815880914135742720967190151836282560618091458852699826141425030123391
10827360384376787644904320596037912449090570756031403507616256247603186379312648
4703743782954975613770...

**2^n algorithm for textures #2**For textures with a dimension X that is not a power-of-two, what's the
best algorithm for calculating the smallest power-of-two greater than
X?
I've been using the following, but is there a simpler way?
int PowerOfTwo(int x)
{
int w = 1;
while (x != 0)
{
w <<= 1;
x >>= 1;
}
return w;
}
...

**Algorithms for X^2 and G^2 Exact Tests?**Does anyone know where I can find the SPSS algorithms for calculating
the exact Pearson X^2 and exact Loglikelihood Ratio G^2 tests? I can
find algorithms for Fisher's, but not these exact tests? In addition,
are there circumstances when these tests can not be relied upon (eg.
very low expected frequencies)?
Thanks.
On 7 Feb 2006 19:27:16 -0800, "LogReg" <mezasocool@hotmail.com> wrote:
> Does anyone know where I can find the SPSS algorithms for calculating
> the exact Pearson X^2 and exact Loglikelihood Ratio G^2 tests? I can
> find algorithms for F...

**2.2.2 Annoyance**Caveat:
Python 2.2.2 (#37, Oct 14 2002, 17:02:34)
Type "help", "copyright", "credits" or "l
>>> l = [1,2,3]
>>> l[1]
2
>>> l.__getitem__(1)
2
>>> l.__getitem__(slice(1))
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: an integer is required
>>>
According to the manuals of Python 2.2.2, passing a slice object to
__getitem__ is all right and should work...
Cost a few (grey) hairs of mine, while debugging a largish program, this is
not so.
Would someone care to pass on th...

**VIBE 2.2 #2**About: Visual Information Broker Enterprise (VIBE) is an IDE that
enables application developers to automate the design and development
of infrastructure components for complex distributed cross-platform,
cross-language systems applications. You can define messages and
generate infrastructure support code for the IBM MQ information bus,
Sybase, Microsoft SQL Server, Oracle, and other JDBC compliant
databases, XML with transformations that use tools like XSL, and J2EE.
It also includes a fully functional Business Rules engine, along with
a graphical programming environment.
Changes: This relea...

**OTM 2.2 #2**Hi all
Just installed OTM on a cust pc (Win XP)
Got a problem that when using the system terminal to access Meridian
Mail, I am unable to exit from mail as the Cntrl ] function is not
recognised.
Now is this a problem with OTM or with the customers PC?
Thanks
Solved it.
The term type was set to VT100 and not VT220
...

**what is 4.2.2.2**Hi
I came to found from many websites when i had a problem in Internet explorer
when if i browse any websites, its showing me "Page cannot be displayed" and
in bottom of the page it shows "Cannot find server or DNS Error" Internet
Explorer that they advised me to put 4.2.2.2 in my Primary DNS Server.
I am in DHCP enabled Network and using windows xp sp2.
My question is what is this ip address mean (4.2.2.2) ? Pl explain in detail.
Can we give it in our Primary DNS server ?
Thanks in advance
Chandra
--
chandra
Message posted via HWKB.com
http:...

**Printing 2^1, 2^2, 2^3, 2^4 and 2^5**Hi,
When I use a while loop, the output is: 2 4 8 16 32, as desired:
<?php
$c=1;
while($c<=5) {
$d = newpow(2, $c);
print "$d ";
$c++;
}
function newpow($base, $power) {
// statements...
}
?>
The But when I use a for loop, the output is: 64:
<?php
for($c=1; $c<=5; $c++);
{
$d = newpow(2, $c);
print "$d ";
}
function newpow($base, $power) {
// statements...
}
?>
Why is this??
Many thanks,
Michael
mejpark wrote:
> When I use a while loop, the output is: 2 4 8 16 32, as desired:
[...]
> The But when I use a for loop, the output is: 64...

**Does 4/2/2= (4/2)/2 =1 OR = 4/(2/2)=4**I don't have matlab and I am trying to translate some simple matlab code.
Does 4/2/2 = (4/2)/2 = 1
or 4/2/2 = 4/(2/2) = 4
On 9/11/2012 9:43 AM, sarah.englander@gmail.com wrote:
> I don't have matlab and I am trying to translate some simple matlab code.
>
> Does 4/2/2 = (4/2)/2 = 1
yes. At a given precedence level (and obviously two of the same
operators are the same level) evaluation proceeds from LtoR.
....snip...
<http://www.mathworks.com/help/techdoc/matlab_prog/f0-40063.html#f0-38155>
--
dpb <none@non.net> wrote in message <...

**how to do this? #2 #2**Hi,
I am working on a program which can do numerical evaluations for
integrations. The program I have is like this,
double foo(p1, p2)
double p1, p2;
{
double kk,step;
int ii;
step_sz=(p2-p1)/100.;
kk=0.;
for (ii=0;ii<100;ii++)
kk+=sin(p1+ii*step_sz)*step_sz;
return (kk);
}
This program used the basic Newton method. My question is here in my program
foo, I can only calculate the integrations for a sine function. If I want to
do an integration for a cosine function, I need to rewrite another function
foo1 with cosine being inserted in. I am sure there is a neat way to do this
wit...

**Levenberg Marquardt**Can anyone recommend a good text that describes exactly and in detail
the Levenberg Marquardt Algorithm?
Thanks
>Richard wrote:
>
> Can anyone recommend a good text that describes exactly and
> in detail the Levenberg Marquardt Algorithm?
>
> Thanks
How about Numerical Recipes?
<http://www.library.cornell.edu/nr/bookcpdf/c15-5.pdf>
Ken
...

**2+2**4
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**2 + 2 =**2 + 2 = 4. Period.
...