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Showing posts from January, 2010

Customised search in Linux using find

Below is a code to customise search in Linux using find. find would recurse through all the directories. I needed to omit some directories which I knew didn't have the file I was looking for but instead have games. So recursing through them would cause enormous processor overhead and time loss. So I wrote a code in shell script to omit specific directories.. cd / for aa in `ls` do if [ "$aa" != "resident_evil" ] ; then if [ "$aa" != "usr1" ] ; then if [ "$aa" != "usr2" ] ; then if [ "$aa" != "usr3" ] ; then if [ "$aa" != "unreal" ] ; then if [ "$aa" != "quake3" ] ; then echo -e " Current search path: " cd $aa pwd find . -name "*.a" fi fi fi fi fi fi cd / done

TT OPE for bc ghosts and massless fermions

While calculating T(z) T(w) OPE for bc ghosts and massless fermions I came across a weird result. I could get the central charge correct and also the T(w)/(z-w)^2 term correct but the other terms which remain does not add up to T(w) as expected. In massless fermion case: T = :ψ ∂ ψ: T(z) T(w) = 1/4/(z-w)^4 + T(w)/(z-w)^2 + ( 1/2 ψ ∂ 2 ψ + ∂ ψ ∂ ψ )/(z-w) But, ∂ T = ψ ∂ 2 ψ + ∂ ψ ∂ ψ So, I cannot account for the 1/2 factor in front of ψ ∂ 2 ψ . In bc ghost case : T = : 2 ∂ c b + c ∂ b : T(z) T(w) = 1/4/(z-w)^4 + T(w)/(z-w)^2 + ( 4 ∂ 2 c b + 3 ∂c ∂b - c ∂ 2 b)/(z-w) But, ∂T = 2 ∂ 2 c b + 3 ∂c ∂b + c ∂ 2 b This means I have some terms like T(z) T(w) = 1/4/(z-w)^4 + T(w)/(z-w)^2 + ( 4 ∂ 2 c b + 3 ∂c ∂b - c ∂ 2 b)/(z-w) = 1/4/(z-w)^4 + T(w)/(z-w)^2 + [∂ T + 2( ∂ 2 c b - c ∂ 2 b)]/(z-w) = 1/4/(z-w)^4 + T(w)/(z-w)^2 + ∂ [ T + 2 ( ∂c b - c ∂b) ]/(z-w) I have no idea why the term ( ∂c b - c ∂b) should be zero. So the problem is: 1. Whether it is correct to directly differe

Convert HTML to PDF

In linux it is very easy. Install CUPS-PDF and print to PDF. I explained it in another post previously. But sadly, if I follow this printing procedure the hyperlinks are not preserved in the resulting pdf file. So the alternatively we can use htmldoc to convert HTML to PDF. The command is - $ htmldoc lec.html --webpage -t pdf14 -f lec.pdf --webpage : turns on the webpage mode. -t : sets the output pdf type. -f : output filename. That's it. If you do not have htmldoc pre-install then install it with sudp apt-get install htmldoc in Ubuntu.

Petrov classification

gr-qc/0512087v1 I read Petrov classification of 4 tensors and Serge classification of 2 tensors. Will it help my project on membrane paradigm? I don't know. But it is good to learn how a 4 tensor can be decomposed. I want to know more of this.