Installing Generic Mapping Tools in Kubuntu

As mentioned in this OpenDX forum, OpenDX is not a gridding tool, so it suggested to try GMT which can be downloaded from http://gmt.soest.hawaii.edu/.
To install this software, it requires NetCDF, so in Kubuntu, use Adept to install:

netcdf-bin
netcdfg-dev

Then, create the GMT input parameter and save it as GMTparam.txt. Download also the install script. Then [...]

How to compress and split into smaller files in Linux

I want to back up a folder that has a size of more than 6GB and then put it into the CD-ROM. To do this, I compress the folder
zip -r /mnt/ESA/Oka/Old.zip Old/

and then split into smaller size using zipsplit. To check how many files will be created if we want to split into 600MB, type
zipsplit [...]

Installing Octave with UMFPACK from Source

if you are not using Ubuntu and need to compile the UMFPACK manually, download the SuiteSparse package at this page. I didn’t use METIS, so I need to disable it first. Follow the instruction at the README.txt on how to disable it. This is the step btw:

from the SuiteSparse directory, go to UFconfig directory [...]

Octave needs UMFPACK for Unsymmetric Sparse Linear Solver

When you install Octave, it will check whether your system has the required libraries. Some of the libraries are optional. However, if you want to solve unsymmetric Sparse linear system, then Octave needs UMFPACK. To install libraries related to sparse matrix in Ubuntu, type
sudo apt-get install libsuitesparse-dev

Measure processing time in Octave

Use cputime() function.
t=cputime;
…%your code
…%computing
…%when you are done
printf(‘Total cpu time: %f seconds\n’, cputime-t);

2D integration from irregular data

How to integrate discrete 2D data?
octave:#> int2d=sum(sum(zdata)).*dx.*dy
But this assumes that the zdata is in a regular mesh with uniform grid spacing dx and dy. If they are irregular, use griddata.
N=100; %number of points;
xreg=linspace(0,max(x),N);
yreg=linspace(0,max(y),N);
dx=xreg(2)-xreg(1);
dy=yreg(2)-yreg(1);
zdatareg=griddata(x,y,zdata,xreg,yreg);
int2d=sum(sum(zdatareg)).*dx.*dy

Purpose of this blog

Well, I usually try to find things on the web to solve my problems, but then I forgot again. So I decided to put it in the blog. So maybe it can help someone else also, out there
ehm most probably about computing, or tips and tricks in doing my projects. yup, it will [...]