On a number axis(One dimension), there are a bunch of points, each point have speed(to left or to right). Compute minumum time that two point meet

I have question about this question. How can I compute the minimum time for two points to meet in O(N) time.

All I can think is brutely compute point pair and get the minimum.

Can anyone give me some hints?

To rotate a point (xa,ya) about (xc,yc) by θ degrees clockwise / counter-clockwise, choice entered by user

I DO NOT GET THE LOGICAL ERROR!

#include <stdio.h> #include <math.h> void main() { float xc,yc,xa,ya,xn,yn,d,r; int n; printf("\nEnter the coordinates of the centre of the stadium: "); scanf("%f %f",&xc,&yc); printf("\nEnter the coordinates of Akash: "); scanf("%f %f",&xa,&ya); printf("\nPress 1 for clockwise, and 2 for anticlockwise movement: "); scanf("%d",&n); printf("\nEnter the angle in degree: "); r=sqrt(pow((xa-xc),2)+pow((ya-yc),2)); scanf("%f",&d); switch(n)     {      case '1':     xn=xc+r*cos(d*3.14/180);     yn=yc-r*sin(d*3.14/180);     break;     case '2':     xn=xc+r*cos(d*3.14/180);     yn=yc+r*sin(d*3.14/180);     break;     } printf("\nNew coordinates of Akash: %f %f",xn,yn); } 

How to rotate a point around a pivot by changing the axis

I’ve been stuck on this forever now because I don’t understand math in the slightest and when people talk about matrices they just give the table and don’t explain how to actually go through each step.

My question is how do I rotate a point around a pivot by moving the axis instead of the point.rotationaroundaxis

        Vector3 center = new Vector3(0.5f,0.5f,0.5f); //an arbitrary center         Vector3 point = new Vector3(0.5f, 0.5f, 0); //an arbitrary point         Vector3 endpoint; //how do I get this          Vector3 current_east = Vector3.right;  //x         Vector3 current_up = Vector3.up; //y         Vector3 current_north = Vector3.forward; //z          Vector3 moveto_east = Vector3.back;         Vector3 moveto_up = Vector3.left;         Vector3 moveto_north = Vector3.up; 

So if I was to rotate the current vectors, to the moveto vectors what position would the point be in. (in this case it would be 0.5, 0, 0.5) buut how would I achieve this assuming the point and the axis will be arbitrarily defined. Picture for clarification.

Why many programming languages and applications use integer instead of floating point to represent time?

In my experience, the value of time mostly is represented by integer number, by programming languages (C/Java/Golang/Javascript(*)…), and by databases (MySQL, Postgres…), exceptions maybe some GUI/game engines and I always think it is normal. But when I thought more about this topic, I found that maybe it makes more sense to represent time in floating point instead.

Some of my points:

  • The value of time is most frequently used in term of continual sequence of events. (eg: is this contract expired yet, is this football match ended yet…). I don’t really remember a time when I need to compare 2 time values are equal. So the precision value of integer is not really useful in this case.
  • Secondly, when the precision time is needed (let say we need to represent exact time like 01/01/2020 UTC). The 64-bit floating point can represent it just fine. Likes in javascript, where the value is represent by number – 64-bit floating point number of milliseconds from epoch.
  • Using 64-bit floating point to store time is actually more space efficient when you need to represent a fraction of unit. Like in golang and C, you need 2 integers (both 64-bit), 1 for number of seconds from epoch, 1 for number of nano seconds.

I can think of some reasons:

  • That’s how hardware(CPU?) works?

So what do you think is the reason(s)? Thanks.

(*) Javascript don’t have native integer type (until recently with BigInt). So the value of date is actually a number, which is 64-bit floating point, but the value is always integer.

virtualbox – How to make “localhost” point to the host’s “localhost”?

I know I can access the host’s localhost using 10.0.2.2. However, what I need is to to be able to type “localhost” in my VirtualBox Edge browser and for it to point to the localhost of my computer.

I have tried a couple thing with the host file, but no success yet. Is it even possible to do what I want?

Cheers!