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Closed 10 years ago.
I have yaw, pitch and roll from an object and i need to transform it into vectorDir and vectorUp. Someone an idea of how to do it?
I would convert the Euler angles (yaw, pitch and roll) into a rotation matrix M. Follow this answer for example.
It is not 100% clear what you need but you it is one of the followings.
You get vectorDir by multiplying the column vector x=[1,0,0] by either M or its transpose.
You get vectorUp by multiplying the column vector z=[0,0,1] by either M or its transpose.
Note. Euler angles are evil, they screw up the stability of your app, see for example
Strange behavior with android orientation sensor,
Reducing wiimote pitch/roll variations.
They are not useful for interpolation either.
Related
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Closed 10 years ago.
I have N points. Each point has X and Y coordinates.
I need to find X and Y of center of mass this points. Can you give me an algorithm to accomplish this task?
Is there something wrong with just taking the weighted average by mass?
for each point n
{
totalmass += n.mass
totalx += n.x*n.mass
totaly += n.y*n.mass
}
center = (totalx/totalmass,totaly/totalmass)
add additional dimensions as appropriate.
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Closed 10 years ago.
I came across this question and couldn't figure out how to approach it. Can someone please help me out? The question is-
Add numbers in base n (not any of the popular ones like 10, 16, 8 or 2 - I hear that Charles Simonyi, the inventor of Hungarian Notation, favors -2 when asking this question).
I just need the idea.
You didn't specify a language, but you could just convert the base n number into a standard integer and add it.
Suppose base N number = '...d2d1d0' where di = the i'th digit.
Number = ... d2 * N^2 + d1 * N^1 + d0 * N^0
Then just add the numbers as usual.
Idea: it looks like hashing, but in hash function you can't use negative numbers.
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Closed 11 years ago.
Please help solve this:
Telephone numbers are often given out as a word representation, so that they are easy to remember. For example if my number is 4357, the text given is HELP. There could be many other possibilities with the same digits, most of which do not make sense.
Write a space-and-time-optimal function that can, given a phone number, print the possible words that can be formed from it.
Based on the detailed explanation in the comment this should be a simple permutation combination problem:
Each digit will have a number of characters associated to it (example 4 could mean either of G,H or I) and then for a combination of digits the permutation can be computed.
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Closed 11 years ago.
How we can to fill the chessboard with domino and we have a some blocks. and chessboard is n x m. and the places filled with ordered numbers.
Test :
Answer like this :
input give n , m and k. k is number of blocks.
and next k lines give blocks such as 6 7 or 4 9.
sorry for my English.
Here's an idea. In your example board, it is immediately obvious that squares 7 9 and 14 must contain domino 'ends', that is to say it must be the case that there are dominos covering 2-7, 8-9, and 14-15.
(In case it's not 'immediately obvious', the rule I used is that a square with 'walls' on three sides dictates the orientation of the domino covering that square)
If we place those three dominos, it may then be the case that there are more squares to which the same rule now applies (eg 20).
By iterating this process, we can certainly make progress towards our goal, or alternatively get to a place where we know it can't be achieved.
See how far that gets you.
edit also, note that in your example, the lower-left corner 2x2 (squares 11 12 16 17) is not uniquely determined - a 90 degree rotation of the depicted arrangement would also work - so you will have to consider such situations. If you are looking for any solution, you must come up with a way of arbitrarily picking one of many possibilities; if you are trying to enumerate all possibilities, you will have to come up with a way of finding them all!
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Closed 11 years ago.
Say you wanted to find which input causes function x to output value y, and you know the (finite) range of possible inputs.
The input and output are both numbers, and positively correlated.
What would be the best way to optimize that?
I'm currently just looping through all of the possible inputs.
Thanks.
One solution would be a binary search over the possible inputs.
Flow:
find the median input x
get the output from function(x)
if the output is less than the desired y
start over using the smaller half of the possible inputs
else
start over using the larger half of the possible inputs
A binary search algorithm, perhaps?
http://en.wikipedia.org/wiki/Binary_search_algorithm
If the range is finite and small, a precomputed lookup table might be the fastest way
if you have some sets of know "x" data that yield "y" you can divied between training and test sets and use neural networks.