Madagascar development blog

• To place tick labels perpendicular to an axis (rather than parallel to it), use parallel#=n, where # is 1, 2, or 3.
.

• To control the tick selection manually, use n#tic=, o#=num, and d#num=.


• To control the label format, use format#= (the argument is a printf-style string)

1. Create a directory called Pylab.


2. Put figure-generating python scripts in this directory.


3. Each script should have a .py suffix


4. Each script should end with a command like savefig('junk_py.eps'); (the name junk_py.eps is important.)

• Plane wave prediction in 3-D

1. OpenMP

OpenMP is a standard framework for parallel applications on shared-memory systems. It is supported by the latest versions of GCC and by some other compilers.

To run a data-parallel processing task like


sfradon np=100 p0=0 dp=0.01 < inp.rsf > out.rsf


on a shared-memory computer with multiple processors (such as a multi-core PC), try sfomp, as follows:.


sfomp sfradon np=100 p0=0 dp=0.01 < inp.rsf > out.rsf


sfomp splits the input along the slowest axis (presumed to be data-parallel) and runs it through parallel threads. The number of threads is set by the OMP_NUM_THREADS environmental variable or (by default) by the number of available CPUs.


2. MPI

MPI (Message-Passing Interface) is a standard framework for parallel processing on different computer architectures including distributed-memory systems. Several MPI implementations (such as MPICH) are available.

To parallelize a task using MPI, try sfmpi, as follows:


mpirun -np 8 sfmpi sfradon np=100 p0=0 dp=0.01 input=inp.rsf output=out.rsf


where the argument after -np specifies the number of processors involved. sfmpi will use this number to split the input along the slowest axis (presumed to be data-parallel) and to run it through parallel threads.

Note: Some MPI implementations do not support system calls implemented in sfmpi and therefore will not support this option.


3. MPI + OpenMP


It is possible to combine the advantages of shared-memory and distributed-memory architectures by using OpenMP and MPI together.


mpirun -np 32 sfmpi sfomp sfradon np=100 p0=0 dp=0.01 input=inp.rsf output=out.rsf


will distribute the job on 32 nodes and split it again on each node using shared-memory threads.


4. SCons


If you process data using SCons, another option is available. Change


Flow('out','inp','radon np=100 p0=0 dp=0.01')


in your SConstruct file to


Flow('out','inp','radon np=100 p0=0 dp=0.01',split=[0],axis=[3,256])


where the optional split=, axis=, and length= parameters contain a list of the sources that you want to split for parallel processing, the axis that needs to be split, and the size of this axis. Then run something like


scons -j 8 CLUSTER='localhost 4 node1.utexas.edu 2' out.rsf


The -j options instructs SCons to run in parallel creating 8 threads, while the CLUSTER= option supplies it with the list of nodes to use and the number of processes to involve for each node. The output may look like


< inp.rsf /RSFROOT/bin/sfwindow n3=42 f3=0 squeeze=n > inp__0.rsf

< inp.rsf /RSFROOT/bin/sfwindow n3=42 f3=42 squeeze=n > inp__1.rsf

/usr/bin/ssh node1.utexas.edu "cd /home/test ; /bin/env < inp.rsf /RSFROOT/bin/sfwindow n3=42 f3=84 squeeze=n > inp__2.rsf "

< inp.rsf /RSFROOT/bin/sfwindow n3=42 f3=126 squeeze=n > inp__3.rsf

< inp.rsf /RSFROOT/bin/sfwindow n3=42 f3=168 squeeze=n > inp__4.rsf

/usr/bin/ssh node1.utexas.edu "cd /home/test ; /bin/env < inp.rsf /RSFROOT/bin/sfwindow f3=210 squeeze=n > inp__5.rsf "

< inp__0.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__0.rsf

/usr/bin/ssh node1.utexas.edu "cd /home/test ; /bin/env < inp__1.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__1.rsf "

< inp__3.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__3.rsf

/usr/bin/ssh node1.utexas.edu "cd /home/test ; < spike__4.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__4.rsf "

< inp__2.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__2.rsf

< inp__5.rsf /RSFROOT/bin/sfradon p0=0 np=100 dp=0.01 > out__5.rsf

< out__0.rsf /RSFROOT/bin/sfcat axis=3 out__1.rsf out__2.rsf out__3.rsf out__4.rsf out__5.rsf > out.rsf


Splitting the input with sfwindow and putting the output back together with sfcat are immediately apparent. The advantage of the SCons-based approach (in addition to documentation and reproducible experiments) is fault tollerance: If one of the nodes dies during the process, one should be able to restart the computation without recreating parts that are already computed.

• Evaluating the Stolt-stretch parameter

• \> Advance one interletter space


• \< Back up one interletter space


• \^Raise one half of a capital letter height


• \_ Lower one half of a capital letter height


• \g Continue processing text, but don't actually print it ("ghostify it").
  This is useful if you want to leave space to go back and add something by hand.


• \G Start printing text again ("deghostify")


• \n Newline


• \h Backspace (control-h also works) back up over the last character


• \- Does nothing; used to prevent a group of characters from being formed into a ligature.


• \\ Print a backslash

• \s# Size change. Change to # percent of the size set in the text vplot. \s100 restores the default height.


• \f# Add # to current fatness. Goes out of effect when text printing is finished.


• \F# Switch to font number #. (-1 restores the default font).


• \k# Move by # space widths to the right (in percent; 100 = one space width). Negative numbers are allowed (moves left).


• \r# Move up # character heights (in percent; 100 = the height of a standard capital letter). Negative numbers are allowed (moves down).


• \v# Print ASCII character number # in the current font, stripping it of any special meaning. This and ligatures are the only way that glyphs numbered greater than 255 are available.


• \c# Switch to color number #. \c-1 restores the current drawing color. Vplot's current drawing color is not changed by changing the color inside text.


• \m# Save current position in register number #.


• \M# Restore position saved in register number #.

title="\s100 \F11 Polinom CHebysheva + \F3 T\_\s75 n\^\s100 (cos \F10 q) = \F3 cos n\F10 q"

original (designed by Rob Clayton at Stanford)


roman simplex


roman duplex


roman complex


roman triplex


italic complex


italic triplex


script simplex


script complex


greek simplex


greek complex


Cyrillic complex

\
German style gothic triplex


Greek style gothic triplex


Italian style gothic triplex


mathematics


miscellaneous

sfplas < RSFSRC/pens/fonts/cyrilc.vplot_font | \

xtpen xcenter=0 ycenter=0 scale=50 pause=1

• High-order kernels for Riemannian Wavefield Extrapolation

• Time-shift imaging condition for converted waves

• Stereographic imaging condition for wave-equation migration