Editing Guide to RSF file format (section)

===Reading LAS files===
LAS (Log ASCII Standard) is a text format used for storing
well-logging data (Heslop et al., 1999<ref>Heslop, K., J. Karst, S. Prensky, D. Schmitt, et al.,  1999, Log ASCII  standard LAS version 3.0: The Log Analyst, 40.</ref>). LAS files can be converted to the RSF format using
<tt>sflas2rsf</tt> utility.
Let us try an example file from one of the SEG tutorials:
<pre>
bash&#36; tutorials=https://raw.githubusercontent.com/seg/tutorials-2014/master
bash&#36; wget &#36;tutorials/1406_Make_a_synthetic/L-30.las
</pre>
Converting to RSF, we can detect 15 different logs:
<pre>
bash&#36; sflas2rsf L-30.las L-30.rsf
(base) sergey@DESKTOP-80QRDA0:~/all/fomels/nnint&#36; sfin L-30.rsf
L-30.rsf:
    in="/home/sergey/RSFROOT/data/L-30.rsf@"
    esize=4 type=float form=native
    n1=15          d1=?           o1=?
    n2=25621       d2=0.5         o2=1140
        384315 elements 1537260 bytes
</pre>
Individual logs are accessible by their keys and can be used in programs like <tt>sfheadermath</tt>.
<pre>
bash&#36; < L-30.rsf sfheaderattr segy=n desc=y
15 headers, 25621 traces
*******************************************************************************
     key                    min                       max                 mean
-------------------------------------------------------------------------------
DEPTH       0           1140 @ 0                 13950 @ 25620            7545
[Depth]
CALD        1           -999 @ 0                19.811 @ 3909         -140.356
[Caliper Caliper - Density]
CALS        2           -999 @ 0                 14.84 @ 23096         7.43849
[Caliper Caliper - Sonic]
DEPT        3           1140 @ 0                 13950 @ 25620            7545
[Depth]
DRHO        4           -999 @ 0                 0.254 @ 23667         -149.67
[Drho Delta Rho]
DT          5           -999 @ 0               199.263 @ 1462          90.0167
[Sonic Delta-T]
GRD         6           -999 @ 0               178.416 @ 21788        -100.952
[GammaRay Gamma Ray - Density]
GRS         7           -999 @ 0               140.148 @ 23376         53.8002
[GammaRay Gamma Ray - Sonic]
ILD         8           -999 @ 0               2022.95 @ 20            34.5917
[DeepRes Deep Induction Standard Processed Resistivity]
ILM         9           -999 @ 0               2196.26 @ 20661         40.5595
[MedRes Medium Induction Standard Processed Resistivity]
LL8        10           -999 @ 0               2097.76 @ 20213         35.6343
[ShalRes Latero-Log 8]
NPHILS     11           -999 @ 0                  0.45 @ 23039        -776.522
[Neutron Neutron Porosity - Ls Mtx]
NPHISS     12           -999 @ 0                 0.615 @ 5215         -373.244
[Neutron Neutron Porosity - Ss Mtx]
RHOB       13           -999 @ 0                 2.811 @ 23941        -147.773
[Density Bulk Density]
SP         14           -999 @ 0               -19.065 @ 20570        -105.029
[SP Spontaneous Potential]
*******************************************************************************
bash&#36; < L-30.rsf sfheadermath output=RHOB segy=n > RHOB.rsf
bash&#36; < RHOB.rsf sfwindow min2=4000 max2=13000 | sfgraph title=Density
</pre>

[[Image:rhob.png|frame|center|Density log.]]