2014/10/15 下午 10:15:44

iphone Programming Glossary: vectors

http://stackoverflow.com/questions/11219240/maximum-speed-from-ios-ipad-iphone

greatly to use Apple's Accelerate framework. It is designed to use the floating point hardware to do calculations on vectors in parallel. I will also address your points one by one 1 This is not because of the CPU it is because as of the armv7 era..

Having trouble decrypting in C# something encrypted on iPhone using RSA

http://stackoverflow.com/questions/1133724/having-trouble-decrypting-in-c-sharp-something-encrypted-on-iphone-using-rsa

Well... the first step as you say you have done is to encrypt the same messages with the same initialization vectors using both the iPhone and the C# implementation. You should get the same output. You said you didn't so there is a problem...

Where can I find an explanation of all transform matrix fields?

http://stackoverflow.com/questions/1260741/where-can-i-find-an-explanation-of-all-transform-matrix-fields

m41 m42 m43 m44 typedef struct CATransform3D CATransform3D This is simply a 4x4 transform matrix used to transform 4 vectors. It can be used to represent any number of linear transforms. See this wikipedia article on this type of matrix. Most of..

adjust corners and crop the image openCV

http://stackoverflow.com/questions/13098073/adjust-corners-and-crop-the-image-opencv

a new image. You should do the following Sort corner points the order matters they must be in the same order in both vectors cv getAffineTransform cv warpAffine I wrote myself a helper function which takes a std vector with four cv Point in it and..

What is DOT3 lighting?

http://stackoverflow.com/questions/1894351/what-is-dot3-lighting

of the light. For two vector the dot product is defined as a dot b a b cos theta where a and b is the length of the vectors a and b respectively and theta is the angle between them. If the length is equal to one a and b are referred to as unit.. and b respectively and theta is the angle between them. If the length is equal to one a and b are referred to as unit vectors and the formula simplifies to a dot b cos theta this means that the diffuse lighting intensity is given by the dot product..

iPhone image stretching (skew)

http://stackoverflow.com/questions/2351586/iphone-image-stretching-skew

on the CATransform3DMake functions. You may need to perform a transpose due to convention of using row or column vectors. To obtain the transform to convert a rectangle X Y W H to any quadrilateral x1a y1a x2a y2a x3a y3a x4a y4a use this function..

Detecting Acceleration in a car (iPhone Accelerometer)

http://stackoverflow.com/questions/2733249/detecting-acceleration-in-a-car-iphone-accelerometer

the numbers look as they should. The difficult part is actually the detection of the forward vector. I am selecting vectors whose magnitude exceeds gravity and from there averaging them and subtracting gravity. I am doing some error checking to.. the iPhone accelerometer was off by a bit which happens more frequently than I would like . But if I plot these vectors that I am using they actually vary by an angle of about 20 30 degrees which can lead to some strong inaccuracies. The end..

Gyroscope vs Accelerometer?

http://stackoverflow.com/questions/3089917/gyroscope-vs-accelerometer

rotates in any its axis you can see a change in rotation. An accelerometer only provides the force along the X Y and Z vectors and cannot solve for twist . By using both sensors you can often implement what is referred to as a 6DOF degrees of freedom..

Using vector graphics in iPhone games

http://stackoverflow.com/questions/5283103/using-vector-graphics-in-iphone-games

is a worry I'd also have a read through the core animation documentation. Core animation uses CALayers to cache vectors drawn with Quartz to in memory bitmaps. These CALayers can then be transformed and translated through the animation APIs...

AES interoperability between .Net and iPhone?

http://stackoverflow.com/questions/538435/aes-interoperability-between-net-and-iphone

. .net iphone encryption aes share improve this question At the very least you are using differing initialization vectors IV . The .Net code uses the key for IV. private static AesCryptoServiceProvider GetProvider byte key Set up the encryption..

Store orientation to an array - and compare

http://stackoverflow.com/questions/6368618/store-orientation-to-an-array-and-compare

tc's question does the orientation relative to North matter I guess not. It is far easier to compare the acceleration vectors than orientations Euler angles rotation matrices quaternions as tc pointed that out. If you are using acceleration data.. angles rotation matrices quaternions as tc pointed that out. If you are using acceleration data you have 3 dimensional vectors at each time point the x y z coordinates. I would simply compute Dist i j SQRT A i X B j X ^2 A i Y B j Y ^2 A i Z B j Z..

Help calculating X and Y from Latitude and Longitude in iPhone

http://stackoverflow.com/questions/6852195/help-calculating-x-and-y-from-latitude-and-longitude-in-iphone

space and angle is the angle between vector 1 and 2 above As a sanity check you could compute the angle of the lat lon vectors created from the top left to bottom left dotted with the bottom right to bottom left. If the angle isn't close to 90 degrees..