Apologies if this is very simple but I have spent weeks coding my first project and there is one part of the puzzle missing!
If I put,
var weatherConditions = prompt ("What are the weather conditions');
is there anyway of assigning certain answers with numerical values that then can be used in mathematical equations further down the page.
For example, if the answer is "warm",
I want the console to register the answer as
var warm = 0.95;
then
var cold = 1.05;
var normal = 1;
Then using that data, I can work out that (100 * warm)
is multiplying 100 by 0.95, rather than the word 'warm' which obviously returns nothing.
Any help hugely appreciated!
I can circumnavigate it to an extent by creating a function and adding it is an attribute, but I really want it to be asked once not repeatedly.
Related
My question is related to plotting amplitude spectrum.
Problem 1: (I have solved it) I have to represent the following function as a discrete set of N=100 numbers separated by time increment of 1/N:
e(t) = 3sin2.1t + 2sin1.9t
I did it using stem function in matlab and plotted it.
Problem 2: (I have question about it) The next thing was to repeat the same above all, using dataset of 200 points with time increment of 1/N and 1/2N.
My question is a bit basic but I just want to clear if I am following the right path to solve my problem.
I want to ask that for problem 2, for both 1/N and 1/2N, should I use N=200 (as I believe it is separate problem)?
A few of my mates have suggested using N=100 for 1/N and N=200 for 1/2N.
which one is the right thing?
Any help will be highly appreciated. Thanks
I have thousand of objects in my app. I wanna make objects visible only at the scene that I see, and make objects invisible out of scene. I wrote a code but it's working laggy. Here is my code :
for(var i:int = 0; i<container.numChildren; i++){
var obj:MovieClip = container.getChildAt(i) as MovieClip;
rectScene.x = -container.x + 25; // position things...
rectScene.y = -container.y + 25;
if(rectScene.intersects(new Rectangle(obj.x-40,obj.y-43,obj.width,obj.height))){
obj.visible = true;
}else{
obj.visible = false;
}
}
Example Image : http://i.stack.imgur.com/GjUG8.png
It's laggy to check all of thousands objects everytime I drag the scene. How can I solve this ?
Thanks a lot !
I would create a Sprite per Scene and add the belonging Object to them. So the display list could look like this:
+root
+-+scene1
+obj1
+obj2
.
.
+objN
+-+scene2
and so on. This way you just need to toggle the current scenes' visibility. But as I see, you are sorting the objects based on intersection with a »scene rect« and that is costly process if you have that many Objects to check. If you cannot add a data structure to associate Objects to Scenes, than you can try to cache the result and run the search only if something changes…
Last but not least you could implement an improved searching algorithm based on space partition, so that you decrease the number of intersection test as much as possible. But that depends on strongly on your application, if everything is moving a lot and you need to update the partition tree very often, that might not be an improvement.
EDIT
One possible algorithm for an efficient lookup of the objects in an area could be orthogonal range searching. An explanation would go too far here and is not the subject of the question.
A book including a nice description is this and a result of a quick and dirty googling is here.
The algorithm is based in a binary tree which contains the coordinates of the objects. If the objects do not move that is perfect for your application, because then the tree just needs to be initialized once and following range queries are quite fast. To be exact, their speed depends on the size of the area to query. So the improvement will be bigger, the smaller the size of the queried area is compared to the size of the overall world.
Good luck!
EDIT #2
I once had a similar thing to handle, that was one dimensional (x-axis only), but as far as I know, it should not be too complicated to make this work in two dimensions (Got that from the book, linked above). You can have a look at the question here.
We all know good old Math.random(). It returns a random floating point number between 0 and 1.
What I can't seem to find any evidence about is if zero or one is exclusive or inclusive.
I know that if they are inclusive, the probability of hitting either one of these values is seriously low.
But I can't help but wonder if I should wasting an if statement looking for it or not.
In my current scenario zero is not a problem, but one is.
var __rand:uint = Math.floor( Math.random() * myArray.length );
var result:String = myArray[__rand];
if the 1 in Math.random() is exclusive, then I will know that will NEVER be 1, and therefore __rand could never equal myArray.length and should always be below it.. But just wasn't sure if I should waste time in some performance critical code if I should account for it.
PS: The code above is NOT the performance critical code, just an example
Basically, just 2 simple questions.
1) Is returning one impossible or possible.
2) If possible, is it worth accounting for it.
As per the docs:
Returns a pseudo-random number n, where 0 <= n < 1. The number
returned is calculated in an undisclosed manner, and is
"pseudo-random" because the calculation inevitably contains some
element of non-randomness.
So it can be 0 but not 1. You don't have to worry about index out of bounds.
By the way, if this was really performance critical code, you are better off casting the value as int or uint rather than using Math.floor (see this performance test).
Math.random will return a number between 0 and (1 exclusive). Never will return a 1.
Using Mathematica I was able to create the following plot
Now I would like to switch to Matlab - which I am just starting to learn. I was able to create the triangulation with FL.vertices and FL.faces matrix and the patch function, that looks like this
faces=FV.faces;
facecolor = [.7 .7 .7];
patch('faces',faces,'vertices',FV.vertices,...
'facecolor',facecolor,'facealpha',0.8,'edgecolor',[.8.8.8]);
camlight('headlight','infinite');
daspect([1 1 1]); axis vis3d; axis off
material dull;
It produces a dull image:
Now, I have a function J that takes the matrix FL.vertices and returns a matrix of positive values. I would like to color the faces according to the values of J on vertices. Possibly interpolate along the faces. Edges can be, for now, as they are - to deal with later. After reading the documentation it is not clear to me how to accomplish this task. Do I need to find min and max of J manually? Or can Matlab do it automatically? It is OK for now to use one of Matlab's preset coloring schemes, something like a "temperature map" would do. At which point should I call my function J? How exactly it should be used with the patch command? I looked through the previous answers to a similar question, but still I am not able to figure out how to deal with my case. Any helping suggestion will be appreciated.
P.S.
OK. I think I did it with simple
FV.Cdata=sphere_jacobian(FV.vertices,1,1,0,1);
figure
Hp = patch('faces',FV.faces,'vertices',FV.vertices,...
'FaceVertexCData',FV.Cdata,'facecolor','interp','edgecolor',[.8 .8 .8]);
But I am not sure if min and max have been automatically computed and interpolated.
Here is what I believe to be the answer given by the poster, I will put it here so the question does not remain open.
OK. I think I did it with simple
FV.Cdata=sphere_jacobian(FV.vertices,1,1,0,1);
figure
Hp = patch('faces',FV.faces,'vertices',FV.vertices,...
'FaceVertexCData',FV.Cdata,'facecolor','interp','edgecolor',[.8 .8 .8]);
But I am not sure if min and max have been automatically computed and interpolated.
I did
colormap(hsv(3200));
and normalized my function:
jac = sphere_jacobian(FV.vertices,m);
minj = min(jac);
maxj = max(jac);
jac1 = (jac-minj*ones(size(jac)))/(maxj-minj);FV.Cdata=jac1;
figure Hp = patch('faces',FV.faces,'vertices',FV.vertices,... 'FaceVertexCData',FV.Cdata,'facecolor','interp','edgecolor',[.8 .8 .8]);
The result can be seen here.
I wrote out a long post trying to explain the exact details of the problem im having, but instead i think ill keep it simple, and ask an example question here:
var n1:Number = 9.99999999999999;
n1 += 0.000000000000009;
var n2:Number = n1 + 10;
var n3:Number = n1 - 10;
Long story short, n1 = 9.99....7, n2 = 20, n3 = 10.
If i try to make a comparison between n1 and n3, they should be the same but they arn't. I dont care if flash rounds it or not, i just need them to be the same (and they arn't, cause flash rounds in one case, and not the other).
Is there some standard solution for a problem like this?
P.S. I dont need this precision on my numbers, but i also would not like to micromanage the rounding of the numbers EVERY time i do a manipulation (that seems like it could add a LOT of code to the mix). If this is the only solution however, i guess ill just have to do a lot of rounding throughout the code, ha.
The Number in flash is a double precision floating point number. Read more here about them. These "problems" are not unique to flash, but just have to do with how these numbers are stored.
There are a couple of options. Here is a quick little library for fuzzy comparing numbers, within a certain margin of error. Another option would be implement a fixed point math library.
Is it a problem to just wrap in int() if you're trying to compare?
trace(int(n1) == int(n3));