General Questions and Answers

Netlib Discussion Forum: Netlib: General Questions and Answers

This is a place to post general questions concerning Netlib or this discussion forum. If you know the answer to any of these, please feel free to post an answer on this page.
By
Randy Brown on Monday, September 21, 1998 - 02:01 pm:

Welcome to the Netlib Discussion Forum. This forum is divided into topics, each of which may contain subtopics. Browse through the topics by clicking on the "Topics" link in the left frame to read and/or post discussions. If you are a new user, you may want to read the Frequently Asked Questions by clicking on the "FAQ" link in the left frame. Also, notice that you can format your messages easily; the "Formatting" link on the left gives the details. Enjoy!!!

By Wangming Lu on Saturday, November 7, 1998 - 05:26 pm:

HI,

I want to solve a set of nonlinear equations, g1(x1,x2,...,xn),...., gn(x1,x2,...,xn), and n can be very large (I am trying 70 for my current project), and I find that under some cases, there are multiple roots for the above set of nonlinear equations, (this leads to the "jump phenomea", and can you tell me what program and what software can get MULTIPLE roots of the above equation instead of just one root.

Meanwhile, I am using the hybrj.f to implement my computation.

thanks

By Vitaly Bulgakov on Thursday, November 12, 1998 - 06:37 pm:

I wonder if anybody knows about industrial
applications in commercial FE software
of preconditioned iterative
methods based on Schur Complement for
independent set orderings.

By Lee Dong-Ki on Friday, November 20, 1998 - 09:54 pm:

Hi,

I want to get a 3D contour(line & fill) algorithm for a single triangular & quadratic mesh to visualize computed stress result on each vertex of that element. I found some Fortran sources here, but these seemed so complicated to me and these are only for 2D. I prefer C-language style code, but Fortran is also OK. Any comments are to be wellcomed from anyone knows about this algorithm.

thanks

By Adatta on Saturday, November 21, 1998 - 08:40 am:

Hi
I want to get a program (software) to minimize
HIGHLY NONLIEAR MULTIVARIATE objective function
with linear constraints.
I will appreciate if anybody helps me regarding
this.

Thanking you

(Alak K. Datta)

By Vijayendra Munikoti on Wednesday, December 23, 1998 - 02:42 am:

Hi
I am looking for a FORTRAN routine for solving the equation which looks something like this:

g11 = f(x,theta,phi); g12 = f1(x,theta,phi) ....
where g11... are the elements of a 3 x 3 matrix.

x is complex.

f = Double integral with respect to "theta" and "phi" with appropriate limits.

The aim is to determine x to satisfy |G| = 0

G = DET[g11,g12,g13; g21,g22,g23;g31,g32,g33] == 0

I would be thankful if anybody could help me regarding this

Thanking you in anticipation

V. Munikoti

By S. Chatterjee on Tuesday, January 5, 1999 - 03:43 am:

i need the complexity for computing the inverse of
a real symmetric matrix using a single processor

please e-mail me if you have an answer

By OrhanORUC on Wednesday, January 6, 1999 - 05:47 am:

I would like to find out an algorithm that fits the ODE system to an experimental data...

By Natasha on Sunday, January 10, 1999 - 08:02 pm:

Hi all

I am currently trying to perform SVD of a complex
general 3x3 matrix using the fortran subroutine
CGESVD.F. Comments within the subroutine state
that on output VT is in fact V**H, rather than
just the matrix V. Has anyone used this code
before and have an idea as to what H is!? I need
to recover the matrix V.

Thanks in advance ....

By Andreas P.F. Bernhard on Friday, January 22, 1999 - 10:38 am:

F77 Compatible BLAS vs F90 builtin linear algebra

Do BLAS routines exist for F90? If not, how do the built in F90 linear algebra routines (eg matmul) compare with calling the F77 BLAS routines.

Thanks

By Alan.Miller on Tuesday, January 26, 1999 - 07:18 pm:

I have BLAS routines written in a subset of F90 at
my web site (
http://www.ozemail.com.au/~milleraj).
They make some use of F90 array syntax.

I would be interested particularly in comments on
routine DNRM2 in level-1 BLAS.

Until recently, my version was based upon Hammarling's code, but I have reverted back to
Lawson's original after finding it much faster
for all 4 compilers on which I tested it.

By Gordon on Wednesday, January 27, 1999 - 02:18 am:

Hi,
My research involves fitting a circle or ellipse in 3D space by means of least squares method on measured datas in the form ( x, y ,z). Does anybody know where I can get the algorithms or source code regarding this. Thanks.

By Priti Mehta on Monday, February 1, 1999 - 04:12 pm:

Hi,

I am looking for some information on
Boeing Harwell Sparse matrix Format. I need
to understand what exactly is this format.
I need to represent a graph/grid with verticies
and edges in a BH format.

Any assisntance or references to such information
is greatly appreciated.

Thanks,
priti

By Bill_allen9 on Thursday, February 18, 1999 - 03:55 am:
By Test on Sunday, February 21, 1999 - 07:03 am:
By Lawrence Walker on Wednesday, February 24, 1999 - 10:25 pm:

I am a newbie at compiling source codes, etc.

I've download the f2c executable for MS-DOS. After converting I get a file that requires 'libf2c.a'. Where (specifically do I get this file? I've looked all over netlib and is simply overwhelmed. How do I compile into Microsoft C++?

Your help is greatly appreciated.

By Ilia on Friday, March 5, 1999 - 02:07 am:

Hi, All.
I'm currently looking for some mailing list about
phisics. If you know one, please tell me.

Ilia Chipitsine <ilia@cgu.chel.su>

By Petero on Friday, March 12, 1999 - 12:32 pm:
By Ben hassen ILyes on Sunday, March 14, 1999 - 09:06 am:

I'd like to configure multiple heterogenous machines (intel, sun ...).One of them will be consedered as the master,the others as slaves. These machines will operate together as a single one to support sequential an parallel programs.
How can I do this ? and what tools do I need ?

Thank's for the help

By Alan Miller on Monday, March 15, 1999 - 01:36 am:

Error in VARPRO.
VARPRO is very old Fortran 66 code for separable
non-linear least-squares fitting. One important
application is in fitting sums of exponentials.
The time constants/ decay rates are the non-linear
parameters; the amplitudes are the linear ones.

In routine VPDPA there is a variable called SAVE.
As its name suggests, it needs to be saved.
I suspect that most Fortran compilers will cough
and splutter over the statement:
SAVE SAVE
so I suggest that SAVE is renamed as say SAVED,
then you can insert the statement:
SAVE SAVED.

I have a version of VARPRO which is compatible
with Lahey's free ELF90 compiler. My e-mail
Alan.Miller @ vic.cmis.csiro.au

By D. Shen on Monday, March 29, 1999 - 04:42 pm:

Hi All,

Does anyone have a c version of LSODA routine? I had some difficulties in converting original fortran program to c using f2c. Thank you very much for your help

By Dennis Lambert on Wednesday, March 31, 1999 - 12:23 am:

Hello,

A class of mine requires me to have access to BLAS functions. I have a Windows 98 machine with Visual C++ 6.0.
Where can I get the libraries to access these functions?
How do I install them once I get them?
Fairly detailed directions would be appreciated as I'm new to all of this.

Thank you,
Dennis Lambert

By Idor on Wednesday, April 21, 1999 - 01:23 pm:

Inverse of a sparse matrix

Does anybody know of any package routines to invert a matrix in a sparse - compressed row - format? are there any in netlib directories?
Thanks.

By Dennis on Thursday, April 22, 1999 - 08:24 am:

Does anybody know how to solve a singular equations, Ax=b, where A is a singular spare matrix?

Thanks alot.

Dennis

By CLabadie on Friday, April 23, 1999 - 10:29 am:

Levenberg-Maquardt:

What is the LAPACK correspondant of the ZXSSQ function of the ISML libraries?

Several Fortran programs I used to fit NMR relaxation data employed the ZXSSQ routine of the IMSL routine (Vax). Is LAPACK the right package to use to solve Levenberg-Maquardt problems?

By Yann on Thursday, May 6, 1999 - 04:56 am:

Hi All

I am trying to simulate and control a continuous system with a software programmed in Java.
I am looking for a JAVA routine for solving ODEs. Does anybody know where I can get algorithms or source code in Java ?

Thanks.

By Dhiru on Thursday, May 13, 1999 - 12:10 am:

hi all

i want to know any program which can be used to
get fourier transform (numerically) for data which
are NOT sampled at a constant sampling frequency.

i have data which is sampled at different times and the times are not an integral multiple of the first.

dhiru

By Manoj Gupta on Tuesday, May 25, 1999 - 05:24 am:

I am using the EISPACK routine for the calculation of the eigen vector and eigen value of a complex general matrix. The routine cg.f and it's dependencies files are used for this. On following the instructions I am getting correct eigen values but not the correct eigen vectors. Please guide me on the issue.

With Regards

By S. vohra on Wednesday, June 2, 1999 - 02:35 pm:

im trying to get the documentation reader for slatec to work
docinstall says to compile and link slprep and subsid, well i try to do that but get an error msg
seb1 /var/tmp> f77 *.f
slprep.f:
MAIN slprep:
ifdeck:
ifif:
ifsid:
pscat:
sort:
subsid.f:
cvtcat:
find:
lenstr:
upcase:
Undefined first referenced
symbol in file
xermsg_ slprep.o
ld: fatal: Symbol referencing errors. No output written to a.out

i checke in slatec/err to see is there is a routine called xermsg, there is not, so any suggestions?

By Hao Wang on Wednesday, June 9, 1999 - 02:44 pm:

Hi:

I am trying to solve Ax=b, A is sparse matrix and huge. I want to use preconditioned biconjugate method. But here I just find program written in Fortran. How and where can I get code in C language.

Tahnks a lot

By Maintainer on Wednesday, June 9, 1999 - 03:07 pm:

RE: biconjugate method

I am not aware of a C routine for this method; however, a fortran-to-C converter can be downloaded from Netlib at http://www.netlib.org/f2c/.

Hope this helps.

By Sanjay on Thursday, June 10, 1999 - 02:06 pm:

this is my second attempt to compile slatec stuff
two questsions

1. seb1 /tmp/src> ar cr libslatec.a *.o
internal error: error_message(58)

what does this mean and how do i get rid of it

2. when a compiled slatec stuff earlier into a library and tried to use it i got for example
using the factorial function fac(4) giving me
floating exception as the answer, i dont think
the library compiled properly, is there a way
to test this.

By Touillon on Friday, June 11, 1999 - 10:46 am:

Hello,

I'm interested in solving automatic problem.
So, I have to use the "poles placement" method.

For the moment, I didn't see any routine witch
I can solve my problem.

Could you be so kind to indicate me if a general
Fortran or C routine is available somewhere ?

Tanks you in advance,
Didier Touillon

By S. Sundar on Monday, July 19, 1999 - 12:31 pm:

hi,
i am trying to solve laplaces eqn in a cube using SOR. i am using neumann boundary conditions such that on every face of the cube except the bottom face, the normal derivative is zero. at the bottom face, the normal derivative is a combination of two gaussians (i am trying to simulate a pair of active regions on the solar surface) - one positive, and one negative. my problem is that the iterations dont proceed beyond a certain number which increases as i decrease the error requirement. if anyone has done this kind of thing before could you tell me if there is some easier method? i am checking to see if the relative error at every point goes below a particular value. any suggestions/references are welcome, since i am new at this.
sundar (ohmwhorules@mailcity.com)

By Harald Schummer on Saturday, July 24, 1999 - 04:02 am:

Hello,

I would like to invert a symmetric hermitian
matrix of the form

R 0 R 1 R 2 R 3
R-1 R 0 R 1 R 2
R-2 R-1 R 0 R 1
R-3 R-2 R-1 R 0

where R-x is the hermetian of Rx.

Any help would be greatly appreciated

By Harald Schummer on Monday, July 26, 1999 - 03:09 am:

Sorry, the matrix I want to invert

R 0 R 1 R 2 R 3
R-1 R 0 R 1 R 2
R-2 R-1 R 0 R 1
R-3 R-2 R-1 R 0

is only hermitian

By James Kellndorfer on Wednesday, August 11, 1999 - 04:59 pm:

I am learning about fourier analysis. As a novice, I have been able to create a power spectrum analysis of a time series or audio signal. And I have can recreate the series from the frequency domain.

My question is how can I use the information on non-periodic data and recreate the wavform's character. For example, project one second in to the future.

I noticed that when I recreate the waveform; the recreated waveform becomes periodic when in fact my original waveform isn't.

Can I use the magnitude and phase angle information to create the non-periodic nature of the waveform?

Or Am I limited to using the base frequency harmonics to reconstruct the waveform?

Lastly, I noticed that when I use the fourier transform information to reconstruct the waveform I get the waveform inverted or it appears graphically 180 degrees out of phase whereas if I use the inverse fourier transform function I can reproduce the waveform precisely.

I don't understand the difference between these two functions. Can someone explain why this occurs?

By M Rahman on Saturday, August 21, 1999 - 02:22 pm:

Hello friends:

For some research work, I need a FORTRAN code for
least square approximation of a function of two variables, say, F(x,y) where the domain of (x,y) is an ellipse with semi-axes (a, b). Therefore, what I need is a FORTRAN code that approximates the function F(x,y) in terms of a polynomial in x and y. Please contact me at mrahman10@hotmail.com or via phone at (248)576-8495. Thank you

By Buddhapriya on Friday, August 27, 1999 - 06:22 am:

I am engaged in solving a non-linear integral equation which as far as I know is the most general fom of a Volterra equation of the second
kind

the form being :

f(x) = g(x) + \int K(x,y)*h(y)dy

Can anyone help? Thanks in advance

Buddhapriya

By Buddhapriya on Friday, August 27, 1999 - 07:28 am:

something I should have added in the previous mail itself is

the x and y are vectors

By Clement Kanyinda on Sunday, August 29, 1999 - 05:18 pm:

Hi friends!

I download 3 bessel subroutines (dbesj0.f, dbesk0.f and dbesi0.f) and I used them 3 months before successfully.

When I come back now to verify some of results, the dbesj0.f doesn't work. I always have a "x outside (-1,1)" message given by dcsevl function.

Are there some hints to solve this problem?. May I remind that I am repeating some data which worked before.

Thanks!

By Simon Peter Benham on Wednesday, October 27, 1999 - 11:51 am:

Hi ,
I am looking for a routine (preferably in f77) to invert a large sparse non-symmetric complex matrix. Please can anybody help ?

Thank You

By Atul deodhar on Tuesday, November 23, 1999 - 09:41 pm:

hi everybody!!

i have a problem where i have to solve the linear
equation given in the subject. the matrix A is of
1200*1200 size.
i want to know whether i can solve the linear
equation using mathematica/ matlab
pl. note that i am a starter in this package

i would 1st ask u whether the code i write in matlab can be converted into an applet of some such thing, so that any person having access to internet can run my program without any problem.
i would appreciate if u would answer this specifically as the computations which would occur are of the order of 1200*1200 size matrix linear equations and involve solving this for some x times(this number though is not very large)
will the user face problems in execution of the
abovesaid code??
this would help me to get really started on the
problem with MATLAB'S help.

also i did go through the commands which are available thru matlab's help and which r pertaining to sparse matix and also to linear equations.
i am curious about the amount of memory used by the software used to solve a large no of simultaneous equations.
i think that the sparse matrix ( 1200 * 1200), with 1200*7 non-zero elements should first be converted into a banded matrix (of 7 bandwidth) and then into a matrix of size 1200*7 with no zero elements.it is now that the linear system should be solved.

the resultant values should now be used to form
another sparse matrix of same features as above and also the steps henceforth followed.
i would like u to tell me if matlab does this in the background or some more efficient method.

By Mark Otto on Monday, November 29, 1999 - 02:44 pm:

I am using f2c (version 19990503) but am having problems concatenating an implicit length string in a subroutine. I wrote a simple test program to show the error. This is the error f2c gives me.

f2c cprob.f
cprob.f:
MAIN:
catit:
Error on line 33 of cprob.f: impossible element in concatenation

The program works without the concatenation line.
Thank you for any help.

c Program to show that a character variable in a subroutine with an indefinite
c length cannot be concatenated.
c Mark Otto, Biological Statistician work: 301-497-5872
c Population and Habitat Assessment Section fax: 301-497-5871
c Office of Migratory Bird Management e-mail: Mark_Otto@FWS.Gov
c U.S. Fish and Wildlife Service
c Department of the Interior
c 11500 American Holly Drive
c Laurel, Maryland 20708-4016

character first*(10),second*(20)
integer lngth
first='Try it. '
second='You''ll like it.'
lngth=14

c Two strings can be cancatenated in the main routine
c Pass the second to a subroutine

write(6,*)'main: ',first(1:10)//second(1:lngth)
call catit(second(1:14))
stop
end

c Give second an implicit length.
subroutine catit(second)
character first*(10),second*(*)
first='Try it. '

c You can print out the inplicit length string but not cancatenate it.
c Test by commenting out the cancatenation step.
write(6,*)'catit: ',second
c write(6,*)'catit: ',first(1:10)//second
stop
end

By Chambers on Monday, November 29, 1999 - 03:53 pm:
By Htpp on Tuesday, November 30, 1999 - 03:30 pm:

test

By Ocsav on Thursday, December 16, 1999 - 05:15 am:

Hi all

Does anybody knows where can i find a good rotine to do neural network modeling ? I am particularly interested in routines using backpropagation method in FORTRAN.

Tx all

By Alan Miller on Saturday, December 18, 1999 - 07:23 am:
By Hari krsihna on Monday, December 20, 1999 - 02:32 am:

Hi everybodY!
If any one knows about the websites related to graph theory or ur doing on this subject please mail me.
I am very need of it.
Expecting reply from you
yours,
hari krishna ravva
ravvas@cyberspace.org

By Alan Miller on Tuesday, December 21, 1999 - 06:10 pm:
By Jack mcmillan on Sunday, February 6, 2000 - 04:22 pm:

I have a very simple (maybe ridiculous) question ,and i hope someone will help. i have downloaded GNu Fortran g77 and i want to know how to access
the 'slatec' subroutine library. i have already
downloaded slatec into a directory c:slatec, so how do i connect it to g77? do i have to put slatec in my autoexec.bat path? do i make other modifications to autoexec.bat? when using g77, do
i write something like "g77 myprogram.f -slatec"
or what? please somebody help me!
i have a compaq presario PC with Windows 98 and DOS.

By Ricardo Fierro on Saturday, February 12, 2000 - 01:07 am:

I want to solve the sparse least squares
problem Ax approx b, where the m-by-n matrix
A has column full rank.

Q1: What are the most commonly used
direct methods?
Q2. Where can reliable Matlab codes
for direct methods be obtained?
Q3. According to the literature, a
symbolic factorization can be done to
find a permutation matrix P such that
the Cholesky factor of the symm pos def
matrix B = (AP)'*(AP) is as sparse as
possible. Is the matrix B formed directly
when the numerical computations are
performed?

--Rick Fierro

By Danyang on Wednesday, February 16, 2000 - 09:16 pm:

I am using Windows NT 4.0 and I want to install f2c. Can someone tell me:

(1) exactly which files I should download? (I know the web page and the readme file confused me.)

(2) How to install f2c?

Thanks.

By Clement Malou on Sunday, February 20, 2000 - 04:35 pm:

Hi,

On my hobby time, I test the CPOLYDR (tompfs/419) which is supposed to give out the zeros of polynomial functions. I was surprised that dealing very simple one, x^2 + 2 x + 4=0, the results was worse. The printing out gives x1=1.7345 and its opposite. Has someones tried it before?

By Alan Miller on Sunday, February 20, 2000 - 09:01 pm:
By Lpj on Friday, February 25, 2000 - 09:51 am:

I have a large non-symmetric matrix eqn to solve. I read that conjugate gradient method requires symmetric positive definite matrix. Is there any variation of the method that I can use? Or any other numerical methods? Direct or iterative?

By Dmitry Izotov on Thursday, March 16, 2000 - 03:59 am:

Hi,

Does anybody know the algorithms solving eigenproblem (faster than Jacoby- or QR -type) for complex matrices of a specific kind: A+i*B, where A is real symmetric, B is real diagonal and i is imaginary unit?
Is there a routine to handle the problem?

By Jennifer Sutherland on Wednesday, March 22, 2000 - 07:51 pm:

I am interested in organizations that do research in Neural Networks. I am interested in specific institutes, companies, or organizsations that are doing research with sparce or limited data as well as applying neural networks to drilling applications. If someone knows of any organizations like this or if you are one could you please email me and send some specific research information.

By Jennifer Sutherland on Wednesday, March 22, 2000 - 07:51 pm:

I am interested in organizations that do research in Neural Networks. I am interested in specific institutes, companies, or organizations that are doing research with sparce or limited data as well as applying neural networks to drilling applications. If someone knows of any organizations like this or if you are one could you please email me and send some specific research information.

By Paul J. Nikolai on Tuesday, March 28, 2000 - 02:24 pm:

The Rutishauser-Reinsch algorithm for partial
solution of the symmetric eigenvalue problem
originally published as ACM TOMS ALGORITHM 538
is currently available in Fortran 90/95.

Kindly see

Paul J. Nikolai
Centerville, OH, USA

By Netvor on Thursday, April 6, 2000 - 06:57 am:
By Alan Miller on Thursday, April 6, 2000 - 10:43 am:
By Dana Williams on Saturday, April 8, 2000 - 01:03 pm:

Hi,
There is a linear programming problem that I am having difficulty with. Can you please help me.
It reads as follows:

The Sweet Tooth Candy Company manufactures and sells 2 products: Crunch Bars and Golden Goodie Bars. The company has a limited supply of 2 chocolate ingredients during the next month: 8,000 ounces of XJ100 and 7,000 ounces of XJ200. Each Crunch Bar uses 0.25 ounce of XJ100 and 0.5 ounce of XJ200. Each Golden Goodie Bar requires 0.5 ounc of XJ100 and 0.25 ounce of XJ200. In addition, the marketing department reports that while the company can seel all the Golden Goddie Bars it can produce, it can only sell up to a Maximum of 10,000 Crunch Bars. Sweet Tooth makes a profit of $0.05 on each Crunch Bar and$0.02 on each Golden Goodie Bar.

QUESTIONS:

1. You can buy more XJ100 and XJ200 from another supplier at a higher price ($0.05 extra per unce of XJ100 or XJ200). Will you purchase more XJ100 and XJ200 and how much? JUSTFY 2. The marketing department claims that a promotion campaign can be used to increse the maximum sale of crunch bars. How much are you willing to spend on such a campaign? JUSTIFY 3. If the production department has invented a new process to make Golden Goodie Bars that can cut production cost and thus increase profit margin of Golden Goodie Bars by$0.10 extra per bar, will that cut the original product mix? JUSTIFY

By J-F. Seurin on Sunday, April 9, 2000 - 01:13 am:

Hello,

I was wondering if anybody out there
had compiled the ARPACK library on a
Windows machine. If so, please let me know
which FORTRAN compiler you used and how
you compiled the library.

Thanks,
J-F. Seurin
Please cc to seurin@uiuc.edu

By Francisco Levinson on Monday, April 10, 2000 - 06:48 am:

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