Opened 7 years ago

Closed 4 years ago

Last modified 3 years ago

#1584 closed defect (fixed)

error in r.walk help page

Reported by: hamish Owned by: grass-dev@…
Priority: major Milestone: 7.2.0
Component: Docs Version: svn-releasebranch64
Keywords: r.walk Cc: Agustin.Lobo@…
CPU: All Platform: All

Description

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.

Change History (7)

comment:1 in reply to:  description ; Changed 7 years ago 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 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.

comment:2 in reply to:  1 Changed 7 years ago by dkavanagh

My note applies to 6.5 and 7.0. The Langmuir correction applies to all versions.

Replying to 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 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.

comment:3 in reply to:  description Changed 7 years ago 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 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.

comment:4 Changed 7 years ago by neteler

Version: unspecifiedsvn-releasebranch64

comment:5 Changed 4 years ago by neteler

Milestone: 6.4.37.1.0

Bumped for check to 7.1. In case backports down to G6.4 are needed.

comment:6 in reply to:  5 Changed 4 years ago by annakrat

Resolution: fixed
Status: newclosed

Replying to neteler:

Bumped for check to 7.1. In case backports down to G6.4 are needed.

I was looking into that recently in 7 and I think it's fine. I backported some of the documentation in r65411.

comment:7 Changed 3 years ago by neteler

Milestone: 7.1.07.2.0

Milestone renamed

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