What does math.hypot, math.abs and math.signmum do?
8bitcarrotjuice wrote ...
2013/8/19
Question
Math.hypot uses the Pythagorean theorem.
So Math.hypot(3, 4) will return 5 (radical of (3^2 + 4^2))
Math.abs returns the absolute value of the given number.
Math.abs(3) will return 3 and Math.abs(-3) will also return 3.
Math.signum returns the signum function of the argument; zero if the argument is zero, 1.0 if the argument is greater than zero, -1.0 if the argument is less than zero.
So, ^ is to the power of, abs does not care about negatives and positives, but I don't get signum? Can you give me an example? Please^10000?
If the value you give to the funktion as parameter is 0 also 0 is returned. If the value is less than 0 (e.g. Math.signum(-5)) -1 will be returned. And if the value is greater than 0 (e.g. Math.signum(5)) 1 is returned.
So it's like a boolean, with 3 states. Can you do this?
Are there other uses?
public void act()
{
int rn=Greenfoot.getRandomNumber(100)-50;
int sgnm=Math.signum(rn);
if(sgnm==1) {
//code
}
if(sgn==0) {
//code
}
if(sgn==-1) {
//code
}
}
Math.signum returns a double value so you'll have to cast the value in line 4 but if you do this it should work.
(1) Can you do this? No problem there; if you wanted a 49 percent chance of 1, 50 percent chance of -1 and only 1 percent chance of 0.
(2) Are there other uses? I have used it in some of my scenarios. Look at the Player class of my Toll-Tally Mad scenario (where I used it to determine the direction of movement in the vertical direction) and in the Ball class of my Pong Pinball scenario (where I used it in determining the world coordinate of the corner of the block that the ball is bouncing off of). It was useful in the second one because the location of the block minus half the width of the image did not always return the correct value since the block actors are rotated (when rotated 90 or 270 degrees the width of the image is actually the height of the actor and the height of the image is actually the width of the actor).
Thanks!
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