Skip to content

added thomas alg in nim #399

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 9 commits into from
Oct 5, 2018
Merged

added thomas alg in nim #399

Show file tree
Hide file tree
Changes from 4 commits
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
818fd32
added thomas alg in nim
c252 Sep 29, 2018
a06341d
Update thomas_algorithm.nim
c252 Oct 3, 2018
b5bdce3
Update thomas_algorithm.nim
c252 Oct 3, 2018
887c35a
Update thomas_algorithm.nim
c252 Oct 3, 2018
755cb2c
Update thomas_algorithm.nim
c252 Oct 4, 2018
d0a22bf
made final edits
c252 Oct 5, 2018
578ca13
deleted .0 and .c files
c252 Oct 5, 2018
1f80db8
Merge branch 'master' into thomas_algorithm_in_nim
c252 Oct 5, 2018
c06e13f
fixed
c252 Oct 5, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
40 changes: 40 additions & 0 deletions contents/thomas_algorithm/code/nim/thomas_algorithm.nim
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,40 @@
const x: array[3,float] = [0.0,2.0,3.0]
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

It's more readable if these are defined after the function. I suspect that you had to do this for the function to know n but that's not the way you should do it.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I could pass the length of the arrays to the thomas_algorithm function. Would that be okay?

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, that would be fine

const y: array[3,float] = [1.0,3.0,6.0]
const z: array[3,float] = [4.0,5.0,0.0]
const w: array[3,float] = [7.0,5.0,3.0]

const n: int = len(w)

proc thomas_algorithm(a,b,c_in,d_in: array[n,float]): array[n,float] =
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

That solution is also not satisfying, you shouldn't rely on a global variable outside of the function, this is basically hardcoding in disguise.


#const n: int = len(d1)

var c: array[n,float] = c_in
var d: array[n,float] = d_in
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This is quite clean I think :)


c[0] = c[0] / b[0]
d[0] = d[0] / b[0]

for i in 1..n-1:
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

There is accidental indentation from here to the end of the procedure. Also n-1 -> n - 1.

let scale: float = (1 / (b[i] - c[i-1] * a[i]))

c[i] = c[i] * scale
d[i] = (d[i] - a[i] * d[i - 1]) * scale

for i in countdown(n-2,0):
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

(n-2,0) -> (n - 2, 0)

d[i] -= c[i]*d[i+1]

return d


echo "The system,"
echo "[1.0 4.0 0.0][x] = [7.0]"
echo "[2.0 3.0 5.0][x] = [5.0]"
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I would write [y] and [z] instead fo [x] everywhere

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

yeah that was a copy paste fail on my part.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Don't forget to fix this :)

echo "[0.0 3.0 6.0][x] = [3.0]"

echo "has the solution:"

const soln: array[3,float] = thomas_algorithm(x,y,z,w)

for i in 0..2:
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Can you calculate this range based on the number of equations again, rather than have it be hard-coded?

echo soln[i]
4 changes: 3 additions & 1 deletion contents/thomas_algorithm/thomas_algorithm.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -113,8 +113,10 @@ You will find this algorithm implemented [in this project](https://scratch.mit.e
[import, lang:"haskell"](code/haskell/thomas.hs)
{% sample lang="swift" %}
[import, lang:"swift"](code/swift/thomas.swift)
{%sample lang="nim" %}
[import, lang:"nim"](code/nim/thomas_algorithm.nim)
{% endmethod %}

<script>
MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
</script>
</script>