CODEWITHSUNDEEP
mathformulaangle
dazzafact
dazzafact

Reputation: 2860

Calculate slope - just with angle

I want to calculate the slope in % for example i just have the angle: (maybe in PHP or Javascript) slope(22.5) //50%

0=0%
22.5=50%
45=100%
67,5=50%
90=0%
112,5=50%
135=100%
180=0
202,5=50%
225=100%
270=0

Upvotes: 2

Views: 1854

Answers (3)

Max
Max

Reputation: 51

Using similar reasoning as paxdiablo I came up with this one-liner

slope = 100*abs(((angle+45) mod 90)-45)/45;

You should be able to see the plot here: go to wolframalpha

Upvotes: 1

paxdiablo
paxdiablo

Reputation: 881293

It appears based on your data that, in each quadrant, you linearly rise from 0 to 100% in the first 45 degrees and drop back down to 0% in the second 45 degrees.

So, you can map all angles into the first quadrant, 0 <= angle < 90, with:

angle = angle % 90

Then if it's in the second half of that quadrant, transform it with a rotation around the 45 degree line with:

if angle >= 45:
    angle = 90 - angle

Now you have an angle 0 <= angle < 45 that's effectively the "distance" from the nearest quadrant boundary, and you can do:

percent = angle * 100 / 45

to get that expressed as a percentage.

So, in short:

angle = angle % 90
if angle >= 45:
    angle = 90 - angle
percent = angle * 100 / 45

As proof of concept, here's some Python code that shows it in action:

for i in range (361):
    angle = i % 90
    if angle >= 45:
        angle = 90 - angle
    percent = angle * 100 // 45
    print("%d -> %d" % (i, percent))

along with the abridged output:

0 -> 0
1 -> 2
2 -> 4
3 -> 6
::
43 -> 95
44 -> 97
45 -> 100
46 -> 97
47 -> 95
48 -> 93
49 -> 91
::
87 -> 6
88 -> 4
89 -> 2
90 -> 0
91 -> 2
92 -> 4
93 -> 6
::
352 -> 17
353 -> 15
354 -> 13
355 -> 11
356 -> 8
357 -> 6
358 -> 4
359 -> 2
360 -> 0

Upvotes: 2

macl
macl

Reputation: 995

slope=abs(tan(angle))*100

¿Is this what you wanted?

Upvotes: -1

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