fortran

Just started all over again:

Installed gfortran, ifortran, lapack, blas and related packages for my research purpose
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gfortran is free and simple.. no linking with terminal is required..

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ifort is tricky:

after installing the offline version of the free intel fortran compiler we need to open the terminal and write this in .bashrc file:

source /home/somu/intel/oneapi/setvars.sh

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installing lapack and lblas is easy from the synaptic package manager and we select the lapack and blas libraries . Hopefully every thing is correct:

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I checked the gfortran and ifort result. its matching exactly and smoothly.

I was writing a code in fortran for exact diagonaliation and needed to compare ifort and gfortran results. Installed the ifort compiler and facing a problem to link lapack and blas library.

This was the problem in the terminal

somenath@fermi ed-wonderfull $ ifort ed-lapack.f90 -llapack -lblas

ld: /usr/local/lib/liblapack.a(xerbla.o): in function `xerbla_':

xerbla.f:(.text+0x55): undefined reference to `_gfortran_st_write'

ld: xerbla.f:(.text+0x60): undefined reference to `_gfortran_string_len_trim'

ld: xerbla.f:(.text+0x77): undefined reference to `_gfortran_transfer_character_write'

ld: xerbla.f:(.text+0x87): undefined reference to `_gfortran_transfer_integer_write'

ld: xerbla.f:(.text+0x8f): undefined reference to `_gfortran_st_write_done'

ld: xerbla.f:(.text+0x9a): undefined reference to `_gfortran_stop_string'

ld: /usr/local/lib/liblapack.a(dormtr.o): in function `dormtr_':

dormtr.f:(.text+0x2dc): undefined reference to `_gfortran_concat_string'

ld: dormtr.f:(.text+0x476): undefined reference to `_gfortran_concat_string'

ld: dormtr.f:(.text+0x4d9): undefined reference to `_gfortran_concat_string'

ld: dormtr.f:(.text+0x521): undefined reference to `_gfortran_concat_string'

ld: /usr/local/lib/liblapack.a(dormql.o): in function `dormql_':

dormql.f:(.text+0x5a7): undefined reference to `_gfortran_concat_string'

ld: /usr/local/lib/liblapack.a(dormql.o):dormql.f:(.text+0x6e4): more undefined references to `_gfortran_concat_string' follow

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What I did was to install

liblapack-dev throgh Ubuntu synaptic package manager and the the problem was solved..

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somenath@fermi ed-wonderfull $ ifort ed-lapack.f90 -llapack -lblas

somenath@fermi ed-wonderfull $ ./a.out

6 20

--LAPACK -2.80277563773199

somenath@fermi ed-wonderfull $

somenath@fermi ed-wonderfull $ gfortran ed-lapack.f90 -llapack -lblas

somenath@fermi ed-wonderfull $ ./a.out

6 20

--LAPACK -2.8027756377319948

=====================================================================

compare ifort and gfortran result

--LAPACK -2.80277563773199

--LAPACK -2.8027756377319948

gfortran options

gfortran -fbounds-check code.f90

./a.out

results:

At line 508 of file code.f90

Fortran runtime error: Array reference out of bounds for array 'nl', upper bound of dimension 1 exceeded (4 > 3)

ifort on complex number

Ifort is not recognising complex intrinsic function. it shows eror. the correct for my compiler is

complex*16, allocatable :: hamA(:,:)

do k=2,L-2

hamA(k,k+1) = cmplx((J1 + J2*al(k+1) + J2*al(k-1))/2.0d0, -J2*(ml(k-1) - nl(k+1))/2.0d0)

end do

Use ifort mkl library for matrix diagonalization (not LAPACK from netlib)

In my research maximum time I do matrix diagonalization. So I write the matrix (or its basis) and call lapack subroutine along with the ifort or gfortran to find the eigenvalues and eigenvectors. For that one has to install lapack library and give the correct path to evoke the lapack routines.

We do something like this. In the terminal where there is a code called mycode.f90

I type

ifort mycode.f90 -llapack -lblas

Now the question is, there is MKL library installed when we install intel fortran compiler. Can we use the MKL library (where LAPACK BLAS routines are there) instead of LAPACK for our purpose?

The standard rule is:

Compile by typing

ifort -mkl mycode.f90

Run by typing

./a.out

Now there can be problem like this:

To solve this problem:

do the following:

Type in the terminal

locate compilervars

You shall see something like this:

Now open the .bashrc file inside your home directory. Add this line

source /opt/intel/composer_xe_2013.3.163/bin/compilervars.sh intel64

This you may have done probably while installing ifort compiler. Then you should not face any above said problem.

After adding this line to .bashrc file compile this by typing in the terminal

source .bashrc

Then exit from the terminal. Go to the folder where your f90 code is. Compile and run you f90 code by -mkl option with ifort. It will work.

ifort -mkl mycode.f90

gfortran options important

There are some useful gfortran options I use regularly.

gfortran -Wall -Wtabs filename.f90
gfortran -fbounds-check filename.f90
gfortran -g filename.f90
1. gdb ./a.out
gfortran -w filename.f90

ifort linux

New ifort license problems?

So,

after installation of ifort (non-commercial for linux) in red-hat there is the problem.

[guest@localhost w0p7-eps0p5]$ ifort

Error: A license for FCompL could not be obtained (-1,359,2).

Is your license file in the right location and readable?

The location of your license file should be specified via

the $INTEL_LICENSE_FILE environment variable.

License file(s) used were (in this order):

1. Trusted Storage

** 2. /opt/intel/composer_xe_2013.3.163/Licenses

** 3. /home/guest/intel/licenses

** 4. /opt/intel/licenses/*.lic

** 5. /Users/Shared/Library/Application Support/Intel/Licenses

** 6. /opt/intel/composer_xe_2013.3.163/bin/intel64/*.lic

Please visit http://software.intel.com/sites/support/ if you require technical assistance.

ifort: error #10052: could not checkout FLEXlm license

Q. How to debug you f90 codes ?

A. One can switch on the warning flags when compiling by ifort.

The commands to remember is follows:

ifort -g -traceback -check all -fp-stack-check mycode.f90

ifort -debug all mycode.f90

Hope these will be working in your case and helpful.

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No LAPACK or BLAS installed along with fortran?

If one is on Mac OS and has not installed LAPACK or BLAS Library, one can do the job of calling LAPACK subroutines as follows. Mac has some inbuilt subroutines which does this jobs. For example:

Instead of this

ifort fortrancode.f90 -llapack -lblas

One can do

ifort fortrancode.f90 -Wl,-framework -Wl,accelerate

This has worked for Mac Pro (Mac OS X 10.6) workstations. I do not know any such things on Linux, though,

One important thing.

If you have installed ifort mkl library there the lapack subroutines are installed by default. The main task is to link them properly and call them during the compilation of your code.

Segmentation fault & Bus error

Very common problem:

ifort :- SIGSEGV, segmentation fault

gfortran :- Bus error

Ifort says:

forrtl: severe (174): SIGSEGV, segmentation fault occurred

Image PC Routine Line Source

a.out 000000010000E265 Unknown Unknown Unknown

a.out 000000010000265D Unknown Unknown Unknown

a.out 0000000100000C2C Unknown Unknown Unknown

a.out 0000000100000BE4 Unknown Unknown Unknown

gfortran says :(only)

Bus error

ifort -traceback

There is one option I know now to check where the possible error could be, is using ifort compiler. One has to insert an option like this:

ifort -heap-arrays 1024 mycode.f90

./a.out

somenath@Kanaad$ifort -traceback main.f90

somenath@Kanaad$./a.out

forrtl: severe (174): SIGSEGV, segmentation fault occurred

Image PC Routine Line Source

a.out 000000010000E732 _sparseform_ 568 main.f90

a.out 0000000100002B5D _MAIN__ 242 main.f90

a.out 000000010000112C Unknown Unknown Unknown

a.out 00000001000010E4 Unknown Unknown Unknown

fortran subroutine

I don't know any gfortran option of this kind.

Unknown Fortran ld: warning:

ld: warning: for symbol _matrix_ tentative definition of size 12944 from /var/folders/uu/uuDNJbYHHwmD3218GxB09U+++TM/-Tmp-//ifort0QNWDs.o is is smaller than the real definition of size 336 from /var/folders/uu/uuDNJbYHHwmD3218GxB09U+++TM/-Tmp-//ifortQ4bnk9.o

Exact Diagonalization Code

click here

DMRG code

click here

How to handle large Array?

The problem is here.

somenath@RamanujanED$

somenath@RamanujanED$ifort sample-matrix-diagonalised.f90 -llapack -lblas

/tmp/ifortRFLH83.o: In function `MAIN__':

sample-matrix-diagonalised.f90:(.text+0x18a): relocation truncated to fit: R_X86_64_32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x194): relocation truncated to fit: R_X86_64_32S against `.bss'

sample-matrix-diagonalised.f90:(.text+0x1b4): relocation truncated to fit: R_X86_64_32S against `.bss'

sample-matrix-diagonalised.f90:(.text+0x26b): relocation truncated to fit: R_X86_64_PC32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x2c0): relocation truncated to fit: R_X86_64_PC32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x315): relocation truncated to fit: R_X86_64_PC32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x36a): relocation truncated to fit: R_X86_64_PC32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x3bf): relocation truncated to fit: R_X86_64_PC32 against `.bss'

sample-matrix-diagonalised.f90:(.text+0x414): relocation truncated to fit: R_X86_64_PC32 against `.bss'

/opt/intel/composer_xe_2011_sp1.9.293/compiler/lib/intel64/libifcore.a(for_init.o): In function `for__signal_handler':

for_init.c:(.text+0xca): relocation truncated to fit: R_X86_64_PC32 against `for__protect_handler_ops'

for_init.c:(.text+0x11b): additional relocation overflows omitted from the output

somenath@RamanujanED$

You can use

ifort -shared-intel -mcmodel=medium codename.f90

there are three mcmodel option

1. -mcmodel=small

2. -mcmodel=medium

3. -mcmodel=large

I acknowledge solution from this website.

http://docs.notur.no/uit/stallo_documentation/error/large-arrays-2gb-memory