trigonometry

问题 I am not clear on what should be the best way to implement sincos(). I've looked up everywhere but it seems the consensus is simply that it is better than doing separate computation of sin and cos. Below is essentially what I have in my kernel for using sincos. However, when I clock it against just doing sin and cos separately it comes out slower. I think it has to do with how I'm using my cPtr and sPtr. Is there a better way? int idx = blockIdx.x * blockDim.x + threadIdx.x; if (idx <

问题 I'm using this piece of code to draw arcs and so far it's been great, however I've encountered an issue with textPath that I cannot figure out. Please run the following snippet. function polarToCartesian(centerX, centerY, radius, angleInDegrees) { var angleInRadians = (angleInDegrees-90) * Math.PI / 180.0; return { x: centerX + (radius * Math.cos(angleInRadians)), y: centerY + (radius * Math.sin(angleInRadians)) }; } function describeArc(x, y, radius, startAngle, endAngle){ var start =

问题 I'm using this piece of code to draw arcs and so far it's been great, however I've encountered an issue with textPath that I cannot figure out. Please run the following snippet. function polarToCartesian(centerX, centerY, radius, angleInDegrees) { var angleInRadians = (angleInDegrees-90) * Math.PI / 180.0; return { x: centerX + (radius * Math.cos(angleInRadians)), y: centerY + (radius * Math.sin(angleInRadians)) }; } function describeArc(x, y, radius, startAngle, endAngle){ var start =

问题 I have a fairly complicated function that takes several double values that represent two vectors in 3-space of the form (magnitude, latitude, longitude) where latitude and longitude are in radians, and an angle. The purpose of the function is to rotate the first vector around the second by the angle specified and return the resultant vector. I have already verified that the code is logically correct and works. The expected purpose of the function is for graphics, so double precision is not

问题 I have a fairly complicated function that takes several double values that represent two vectors in 3-space of the form (magnitude, latitude, longitude) where latitude and longitude are in radians, and an angle. The purpose of the function is to rotate the first vector around the second by the angle specified and return the resultant vector. I have already verified that the code is logically correct and works. The expected purpose of the function is for graphics, so double precision is not

问题 I'm writing a function that evaluates how many pixels overlap between two non-isosceles trapezoids. In my application, a trapezoid is always defined as : typedef std::array<cv::Point, 4> Trapezoid; //[0] - bottom left //[1] - bottom right //[2] - top right //[3] - top left Additionally, these trapezoids will have the properties that indexes [0] and [1] will always have the same Y as will [2] and [3] (Always parallel to Y axis). So, let's say I have two trapezoids: //300 high, 100 top, 200

问题 This question already has answers here : Is floating point math broken? (31 answers) Closed 3 years ago . From mathematics we know that the cosine of a 90 degree angle is 0 but Python says it's a bit more than that. import math math.cos(math.radians(90)) 6.123233995736766e-17 What's the matter between Python and the number "0"? 回答1: Repeat after me: Computers cannot process real numbers. Python uses double precision IEEE floats, which round to 53 binary digits of precision and have limits on

问题 I am getting wildly diverging distances using two approximations to calculate distance between points on Earth's surface. I am using the Haversine (vectorized) approximation and the more precise (presumably) geopy.distance.geodesic . As you can see I am off by five percent as the distances between points becomes large. Is this divergence due to rounding error in Haversine? Do I indeed trust the Geodesic? Here is code: import numpy as np lat = np.linspace(35,45,100) lon = np.linspace(-120,-110

问题 I get some GPS coordinates from Google Maps and I need to find the distance between them using Objective C. I have implemented the formula but I get results that are way to big. I have tested the values from Google Maps by passing them back into Google Earth and a Geocoding service on the internet and everything checks out. Im now beginning to suspect that the cosine law demands I do some sort of conversion with the coordinates before I pass them in. I did a similar implementation of the

问题 this seems like such a simple problem but I have been unable to find an answer (and im no good at math). I am trying to move a UIView to a new CGPoint X distance away along a certain heading. What is the formula for determining the new coordinates? (i do no want this to be animated, just an instantaneous move) something like: x = 100; (current x value) y = 150; (current y value) d = 25; (distance to move the point) h = 90; (west) \\\ insert formula to determine new x,y coords self.car.center