Recent content by fineTuner

##\Omega^n## can be obtained multiplying the matrix n times. I underestimated the definition of ##e^{\Omega}##, i guess i can't obtain it taking the exponential of each element... now I'm reading the definition on wikipedia.

Homework Statement Given the matrix $$ \Omega = \begin{pmatrix} 0 & -\psi & 0 & 0 \\ -\psi & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \end{pmatrix}$$ show that ## e^{\Omega}## is a Lorentz transformation along the x-axis with ## \beta = tanh(\psi)## Homework Equations During the lesson we...

You're right! I used this formula: THETA = (!pi/2.)*(1.-THETA/90.) I solved all the problems, the map is correct! Thank you Chalnoth :)

No, that's why i decided to use the write_fits_cut4 routine, that uses the pixIndex array and the original TEMPERATURE array. Then i plotted the map with mollview (it works!). ;Map creation nside=512 ang2pix_ring, nside, AR, DEC, pixIndex WRITE_FITS_CUT4,'Mappa.fits', pixIndex...

I set nside = 1024. Now i don't calculate npix because ang2pix_ring needs only nside to work (i also took a look to the source code). So, here's the new code (now I'm using degrees for coordinates), but the error remains the same: pro makemap init_healpix...

Ok, i'll make a coordinate transformation using that routine! Using this formula (writing before that nside = 1024), it reports this: WRITE_FITS_MAP: Non-Healpix data set npix = 28121 nside = -1 *** file NOT written ! *** Mappa.fits not found (28121 is the number...

Is coordinate change necessary? Can i produce the map with celestial one? Here's my code: pro makeMap init_healpix ;From data file to 3 arrays OPENR, lun, 'dati.txt', /GET_LUN nLines = FILE_LINES('dati.txt') data = FLTARR(4, nLines)...

Here's an example: 78.002930 -40.033035 84.2312 60.1127 The order is AR, DEC, DATA (uK), dummy. The 4th column isn't necessary. I found this tutorial https://www.idlcoyote.com/tips/ascii_column_data.html Now I'm going to work on this. I think it's an easy task (i'm starting...

Unfotunately i have to use healpix, even if i haven't a full-sky map! So, i need to use the ring scheme. The manual (http://healpix.jpl.nasa.gov/html/intronode4.htm) says that with this scheme the Fourier transform is easy to implement (after the map i'll have to plot the angular power...

Hi Chalnoth and thank you, unfortunately i don't have the data in FITS format, only .txt file. The data comes from a balloon experiment for CMB measurements, so it covers only a limited sky region (no objects on particular). Should i convert the .txt file in FITS?

Hi, i've just installed Healpix on IDL, and I'm starting to try all the subroutines. First of all, i learned how to make a dipole map with random numbers (it works!:) ). Now i'd like to plot a map using real data. The .txt file is organized like this: DEC(°) AR(°)...

Hi! Thank you JJacquelin and HallsofIvy for your answers. The most useful form is the first one, in the matrix form. I will put it into a f90 program to simulate a body orbiting around a planet with air drag... now it's time to find the right units to avoid problems with my pc, let's see what...

Hi, i have to reduce the order of a 2nd order differential equation, to solve it with a numerical method. The equation is: \ddot{r}+a\dot{r}+\frac{b}{r^{2}}=0 with a,b\geq0 I tried to reduce it substituting \dot{r}=v, but i don't know what to do with the term \frac{b}{r^{2}} ...

Yes, i read the whole guide, and there is only that section about GDL. I decided to use GDL because i don't have IDL for Linux, but only for Windows. Well, i'll try to find another solution!

Hi Chalnoth, yes i sent a reply but i made some mistakes so i deleted it, sorry. I've installed Ubuntu and GDL and I'm learning to use it. I also downloaded the Healpix folder and I'm trying to install it (i'm following the official guide). I unpacked the folder, its path is...