Opened 11 years ago
Closed 9 years ago
#8245 closed defect (fixed)
tutorial: typo in section "Euler’s Method for Systems of Differential Equations"
Reported by: | mvngu | Owned by: | mvngu |
---|---|---|---|
Priority: | minor | Milestone: | sage-4.8 |
Component: | documentation | Keywords: | beginner sd35.5 |
Cc: | kcrisman | Merged in: | sage-4.8.rc0 |
Authors: | Kenneth Smith | Reviewers: | Karl-Dieter Crisman |
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
From sage-support:
In the section, "A Guided Tour"->"Basic Algebra and Calculus"- >"Euler’s Method for Systems of Differential Equations", I found that the answer of the example is z(1)≈0.75, which seems to be wrong. The calculation is ------------------------------------------------------------------------ sage: t,x,y = PolynomialRing(RealField(10),3,"txy").gens() sage: f = y; g = -x - y * t sage: eulers_method_2x2(f,g, 0, 1, 0, 1/4, 1) t x h*f(t,x,y) y h*g(t,x,y) 0 1 0.00 0 -0.25 1/4 1.0 -0.062 -0.25 -0.23 1/2 0.94 -0.12 -0.48 -0.17 3/4 0.82 -0.16 -0.66 -0.081 1 0.65 -0.18 -0.74 0.022 ------------------------------------------------------------------------ So I think the right answer should be z(1)≈0.65
Attachments (1)
Change History (10)
comment:1 Changed 11 years ago by
- Keywords beginner added
comment:2 Changed 10 years ago by
- Cc kcrisman added
comment:3 Changed 9 years ago by
- Description modified (diff)
Changed 9 years ago by
comment:4 Changed 9 years ago by
- Status changed from new to needs_review
comment:5 Changed 9 years ago by
- Keywords sd35.5 added
comment:6 follow-up: ↓ 7 Changed 9 years ago by
- Reviewers set to Karl-Dieter Crisman
- Status changed from needs_review to positive_review
And the math turns out to be right. The example itself is somewhat elliptically expressed, but this is fine.
Curious as to why we have both :math:
and the backticks... but anyway, that would be a general overhaul of the tutorial.
comment:7 in reply to: ↑ 6 ; follow-up: ↓ 8 Changed 9 years ago by
Replying to kcrisman:
Curious as to why we have both
:math:
and the backticks... but anyway, that would be a general overhaul of the tutorial.
Within Sage, `foo`
is equivalent to :math:`foo`
. In general ReST code, this is not true.
comment:8 in reply to: ↑ 7 Changed 9 years ago by
Curious as to why we have both
:math:
and the backticks... but anyway, that would be a general overhaul of the tutorial.Within Sage,
`foo`
is equivalent to:math:`foo`
. In general ReST code, this is not true.
Ah, so it's historical in that sense. Thanks for the clarification.
comment:9 Changed 9 years ago by
- Merged in set to sage-4.8.rc0
- Resolution set to fixed
- Status changed from positive_review to closed
I just made that one change making the 7 a 6.