Hello, I'm new to haskell. I want to write a function for a s-curve acceleration in haskell. A solution in VBA is already working. Are there nested guards in haskell available or how can I rewrite this function? The function should calculate the acceleration for a given distance, max acceleration, velocity, jerk at time since start acc_skurve::Float->Float->Float->Float->Float->Float acc_skurve str acc v jerk taktuell | str <= str2jerk |taktuell <= (0.5 * str / jerk)**(1/3::Float) = jerk * taktuell |taktuell <= (4 * str / jerk)**(1/3::Float) = jerk**(2/3::Float) * 2**(2/3::Float) * str**(1/3::Float) - jerk * taktuell |taktuell <= (27/2 * str / jerk)**(1/3::Float) = - jerk * taktuell + 2**(2/3::Float) * str**(1/3::Float) * jerk**(2/3::Float) |taktuell <= (32 * str / jerk)**(1/3::Float) = -2 * 2**(2/3::Float) * str**(1/3::Float) * jerk**(2/3::Float) + jerk * taktuell | str > str2jerk && str < str2acc |taktuell <= acc / jerk = jerk * taktuell |taktuell <= - acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc |taktuell <= acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc / 2 - jerk * taktuell + sqrt(acc^3 + 4 * str * jerk^2) / (2 * sqrt(acc)) |taktuell <= 3 * acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc / 2 - jerk * taktuell + sqrt(acc^3 + 4 * str * jerk^2) / (2 * sqrt(acc)) |taktuell <= sqrt(acc^3 + 4 * str * jerk^2) / (sqrt(acc * jerk)) = - acc |taktuell <= acc / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (sqrt(acc * jerk)) = - acc + jerk * taktuell - sqrt(acc^3 + 4 * str * jerk^2) / sqrt(acc) | str >= str2acc |taktuell <= acc / jerk = jerk * taktuell |taktuell <= v / acc = acc |taktuell <= acc / jerk + v / acc = acc - jerk * taktuell + v * jerk / acc |taktuell <= str / v = 0 |taktuell <= str / v + acc / jerk = jerk * str / v - jerk * taktuell |taktuell <= str / v + v / acc = - acc |taktuell <= str / v + acc / jerk + v / acc = -(str / v + acc / jerk + v / acc - taktuell) * jerk where str2jerk = 2 * acc^2 / jerk^2 str2acc = acc^2 * v + v^2 * jerk / (jerk * acc) best regards Thomas
http://www.haskell.org/haskellwiki/Case That link shows how to write a select function that offers functionality similar to a switch statement in C. Then you could use guards for the top-level switching and the select function for the second level. On Fri, 3 Feb 2012 19:55:03 +0100, Thomas Engel wrote:
Hello,
I'm new to haskell. I want to write a function for a s-curve acceleration in haskell. A solution in VBA is already working.
Are there nested guards in haskell available or how can I rewrite this function?
The function should calculate the acceleration for a given distance, max acceleration, velocity, jerk at time since start
acc_skurve::Float->Float->Float->Float->Float->Float acc_skurve str acc v jerk taktuell | str <= str2jerk |taktuell <= (0.5 * str / jerk)**(1/3::Float) = jerk * taktuell |taktuell <= (4 * str / jerk)**(1/3::Float) = jerk**(2/3::Float) * 2**(2/3::Float) * str**(1/3::Float) - jerk * taktuell |taktuell <= (27/2 * str / jerk)**(1/3::Float) = - jerk * taktuell + 2**(2/3::Float) * str**(1/3::Float) * jerk**(2/3::Float) |taktuell <= (32 * str / jerk)**(1/3::Float) = -2 * 2**(2/3::Float) * str**(1/3::Float) * jerk**(2/3::Float) + jerk * taktuell | str > str2jerk && str < str2acc |taktuell <= acc / jerk = jerk * taktuell
|taktuell <= - acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc
|taktuell <= acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc / 2 - jerk * taktuell + sqrt(acc^3 + 4 * str * jerk^2) / (2 * sqrt(acc))
|taktuell <= 3 * acc / 2 / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (2 * jerk * sqrt(acc)) = acc / 2 - jerk * taktuell + sqrt(acc^3 + 4 * str * jerk^2) / (2 * sqrt(acc)) |taktuell <= sqrt(acc^3 + 4 * str * jerk^2) / (sqrt(acc * jerk)) = - acc
|taktuell <= acc / jerk + sqrt(acc^3 + 4 * str * jerk^2) / (sqrt(acc * jerk)) = - acc + jerk * taktuell - sqrt(acc^3 + 4 * str * jerk^2) / sqrt(acc)
| str >= str2acc |taktuell <= acc / jerk = jerk * taktuell
|taktuell <= v / acc = acc |taktuell <= acc / jerk + v / acc = acc - jerk * taktuell + v * jerk / acc |taktuell <= str / v = 0 |taktuell <= str / v + acc / jerk = jerk * str / v - jerk * taktuell |taktuell <= str / v + v / acc = - acc |taktuell <= str / v + acc / jerk + v / acc = -(str / v + acc / jerk + v / acc - taktuell) * jerk where str2jerk = 2 * acc^2 / jerk^2 str2acc = acc^2 * v + v^2 * jerk / (jerk * acc)
best regards Thomas
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On 3 February 2012 20:16, David Frey
http://www.haskell.org/haskellwiki/Case
That link shows how to write a select function that offers functionality similar to a switch statement in C. Then you could use guards for the top-level switching and the select function for the second level.
Yikes - that idiom is rather horrible, vis packing cases into a list so they can be consumed by a function. To solve the problem, I'd seek a more "mathy" description of the algorithm i.e. one that doesn't use conditionals so heavily and work from that rather than translate existing code.
participants (3)
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David Frey -
Stephen Tetley -
Thomas Engel