Recent content by nburo

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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    Thank you, but I think one of your 6 equations might be dependent of the others. (equation 6, I think)
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    F, H and J are fixed. I'm studying this particular case.
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    I get why IB = IC, but not the IB = IC = 2r
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    Here you go.
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    I must admit I am very interested by your solution. I'm looking forward for more hints you might have. Thanks to both of you for taking your time. It's really appreciated.
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    Oh well, thank you!
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    I misspelled theta, sorry. You might want to ignore them, if they are not necessary (sorry for the confusion). They might become handy later on, when this problem is solved. The context of this problem is related to pool/billiards. To make long story short, A is the ball you want to pot...
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    Undergrad Simple Geometry Problem: Finding the Delta Angle in an Irregular Quadrilateral

    "Simple" geometry problem Hello everyone, I need your help in this "simple" geometry problem. I need to find the delta angle, knowing everything else given into the image (see attachment). It might even not be possible at all, for all I know. I've tried very hard, but I still have no...
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    Graduate Differential Equation with Vectors

    Wow thanks guys! Your responses are very interesting and useful! Unfortunately, I don't really know much about the Runge-Kutta method =/
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    Graduate Differential Equation with Vectors

    Thanks, but ok, le's say I decomposed it in 3 differential equations. Here I'll have : \frac{d}{dt}\theta_1(t) = F(\theta_1(t), \theta_2(t), \theta_3(t) ) \frac{d}{dt}\theta_2(t) = F(\theta_1(t), \theta_2(t), \theta_3(t) ) \frac{d}{dt}\theta_3(t) = F(\theta_1(t), \theta_2(t), \theta_3(t) )...
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    Graduate Differential Equation with Vectors

    Hello everyone, I have the following differential equation : \dot{\theta}(t) = \omega(t) - \frac{1}{2}\theta(t)\times\omega(t) + \frac{1}{\Vert\theta(t)\Vert^2}\left(1-\frac{\Vert\theta(t)\Vert}{2}cot\frac{\Vert\theta(t)\Vert}{2}\right)\theta(t)\times[\theta(t)\times\omega(t)] where...
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    Graduate What is the derivative of a quaternion with a changing unit vector?

    Thank you D H. In my problem, I need to rotate, not to transform, i.e. every equation must be in a global/fixed frame. Which notation should I use?
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    Graduate What is the derivative of a quaternion with a changing unit vector?

    WHAT? You know that? :biggrin: WOW Thks, but I already knew =) I was too lazy to type it, that's why :P I use LaTeX every at work. It's a so powerful tool!
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    Graduate What is the derivative of a quaternion with a changing unit vector?

    You're one quaternion beast! :wink: Before using our new equation, my research boss told me to do something. David Baraff published some article in Siggraph '97. He developped a proof that even when û(t) is not constant, a quaternion time derivative can be expressed this way ...
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    Graduate What is the derivative of a quaternion with a changing unit vector?

    Haha =) I get it, sorry =P Also, with B = [cosφ/2, êsinφ/2]A, does that mean I can simply substitute B by that in my main interpolation equation? What about my time substitution in interpolation? Is it alright? :cool: