#1584: error in r.walk help page
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Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.3
Component: Docs | Version: unspecified
Keywords: r.walk | Platform: All
Cpu: All |
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one from Agustin:
{{{
the documentation in r.walk is wrong. It says:
"The default values for a, b, c, d are those proposed by Langmuir
(0.72, 6.0, 1.9998, -1.9998)"
and it should say:
"The default values for a, b, c, d are those proposed by Langmuir
(0.72, 6.0, -1.9998, 1.9998)"
because the point is that you go faster on gentle slopes and more
slowly on steeper slopes and those values are in m/s
The worrying question is whether these values are also wrong in the
default values of r.walk.
}}}
#1584: error in r.walk help page
--------------------+-------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.3
Component: Docs | Version: unspecified
Keywords: r.walk | Platform: All
Cpu: All |
--------------------+-------------------------------------------------------
Comment(by dkavanagh):
There is also a mistake in the Standard Directions figure in the Movement
Direction section. 90 should be immediately below x and the zero should be
removed.
Replying to [ticket:1584 hamish]:
> one from Agustin:
>
> {{{
> the documentation in r.walk is wrong. It says:
> "The default values for a, b, c, d are those proposed by Langmuir
> (0.72, 6.0, 1.9998, -1.9998)"
> and it should say:
> "The default values for a, b, c, d are those proposed by Langmuir
> (0.72, 6.0, -1.9998, 1.9998)"
>
> because the point is that you go faster on gentle slopes and more
> slowly on steeper slopes and those values are in m/s
> The worrying question is whether these values are also wrong in the
> default values of r.walk.
> }}}
#1584: error in r.walk help page
--------------------+-------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.3
Component: Docs | Version: unspecified
Keywords: r.walk | Platform: All
Cpu: All |
--------------------+-------------------------------------------------------
Comment(by dkavanagh):
My note applies to 6.5 and 7.0. The Langmuir correction applies to all
versions.
Replying to [comment:1 dkavanagh]:
> There is also a mistake in the Standard Directions figure in the
Movement Direction section. 90 should be immediately below x and the zero
should be removed.
>
> Replying to [ticket:1584 hamish]:
> > one from Agustin:
> >
> > {{{
> > the documentation in r.walk is wrong. It says:
> > "The default values for a, b, c, d are those proposed by Langmuir
> > (0.72, 6.0, 1.9998, -1.9998)"
> > and it should say:
> > "The default values for a, b, c, d are those proposed by Langmuir
> > (0.72, 6.0, -1.9998, 1.9998)"
> >
> > because the point is that you go faster on gentle slopes and more
> > slowly on steeper slopes and those values are in m/s
> > The worrying question is whether these values are also wrong in the
> > default values of r.walk.
> > }}}
#1584: error in r.walk help page
--------------------+-------------------------------------------------------
Reporter: hamish | Owner: grass-dev@…
Type: defect | Status: new
Priority: major | Milestone: 6.4.3
Component: Docs | Version: unspecified
Keywords: r.walk | Platform: All
Cpu: All |
--------------------+-------------------------------------------------------
Comment(by dkavanagh):
Hamish - I believe the help is correct. c and d are multiplied by the
delta, which in a downward slope will be negative. Here is an example from
the code - fcost_dtm = (double)((double)(W_dtm - my_dtm) * c);
Replying to [ticket:1584 hamish]:
> one from Agustin:
>
> {{{
> the documentation in r.walk is wrong. It says:
> "The default values for a, b, c, d are those proposed by Langmuir
> (0.72, 6.0, 1.9998, -1.9998)"
> and it should say:
> "The default values for a, b, c, d are those proposed by Langmuir
> (0.72, 6.0, -1.9998, 1.9998)"
>
> because the point is that you go faster on gentle slopes and more
> slowly on steeper slopes and those values are in m/s
> The worrying question is whether these values are also wrong in the
> default values of r.walk.
> }}}