Good afternoon
From the function “r.flow” (https://grass.osgeo.org/grass78/manuals/r.flow.html), can some expert explain me what is the meaning of: “val-th” and the meaning of: “max(1, <rows in elevation>/50, <cols in elevation>/50).”
Thanks in advance
Regards
Cumprimentos,
Valter Albino - Geógrafo Físico, M.Sc.
Modelação H&H / Riscos ambientais / OT&U
Valter Albino wrote
Good afternoon
From the function "r.flow" (
https://grass.osgeo.org/grass78/manuals/r.flow.html), can some expert
explain me what is the meaning of: "val-th" and the meaning of: "max(1,
<rows
in elevation>
/50,
<cols in elevation>
/50)."
no expert here on my side, though, from the manual:
skip=integer
Number of cells between flowlines
Another option, skip, indicates that only the flowlines from every val-th
cell are to be included in flowline.
=> it may be something like: val-th value is the threshold value given by
skip
The default skip is max(1, <rows in elevation>/50, <cols in elevation>/50)
=> it's the calculation of the default skip value if no skip=integer figure
is given.
see the r.mapcalc manual:
https://grass.osgeo.org/grass78/manuals/r.mapcalc.html
max(x,y[,z...]) largest value of those listed
contribution for precising the manual welcome.
-----
best regards
Helmut
--
Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html
Good evening Helmut,
Thank you for reply (nice try, expert 
).
Don’t understand the presence of 1, he is absent in the formula. Neither the choice of number 50.
So, in a spreadsheet is something like the following example:
=MÁXIMO(1,150/50,338/50)=6.76
If using 10:
=MÁXIMO(1,150/10,338/10)=33.80
Regards
Helmut Kudrnovsky <hellik@web.de> escreveu no dia segunda, 3/02/2020 à(s) 18:09:
Cumprimentos,
Valter Albino - Geógrafo Físico, M.Sc.
Modelação H&H / Riscos ambientais / OT&U
OOps,
One example was wrong (this other for example: =MÁXIMO(1,35/50,250/50)=5.00)
Valter Albino <valteralbino@gmail.com> escreveu no dia segunda, 3/02/2020 à(s) 19:46:
Cumprimentos,
Valter Albino - Geógrafo Físico, M.Sc.
Modelação H&H / Riscos ambientais / OT&U
Don't understand the presence of 1, he is absent in the formula. >Neither
the choice of number 50.
you're right, the ultimative authority is the source code
https://github.com/OSGeo/grass/tree/master/raster/r.flow
someone more familiar with these lines of code will probably have a better
answer
-----
best regards
Helmut
--
Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html
Thanks Helmut!
Helmut Kudrnovsky <hellik@web.de> escreveu no dia segunda, 3/02/2020 à(s) 21:07:
Cumprimentos,
Valter Albino - Geógrafo Físico, M.Sc.
Modelação H&H / Riscos ambientais / OT&U