Drawing Custom 2D Graph : Need Help!

Question

Hi,
I'm new to this forum, but I figured this would be the best place to ask for help.
I'm currently working on a new project; a Graphing Calculator for algoriths and such. I've been with Java for a while now, but I have ran into a few snags with my new project.
[1] For now, I have a line wizard that seperates a algorithm (linear, polynomial only for now) into chunks. How would I go out Parsing it totally from a string, in any format. I need to include such mathmatical operations such as sin( , cos( and ect. I have not even started on a rough draft yet, because I don't know where to start.
[2] My custom GraphClass is having a hard time repersenting different rates for minium and maxium axis size. For some reason both axis wont draw in the right spot, meaning my X() and Y() are coded wrong. This is some of my code for now:
For the full class file goto : [http://pastebin.com/Ty9ndCc4]
public int width = 390;
public int length = 390;
public static int minX = (int) -200;
public static int maxX = (int) 200;
public static float XScale = 390/ ( Math.abs(maxX)  +Math.abs(minX) );+
+public static int minY = (int) -200;+
+public static int maxY = (int) 200;+
+public static float YScale = 390/ ( Math.abs(maxY)+  Math.abs(minY) );
public static int X() {
     return (int) ((int) Math.round(abs(minX)*(float)XScale));*
*public static int Y() {*
*return (int) 390 - ((int) Math.round(abs(minY)*(float)YScale)); // 390 -  *because of the Y axis being upside down*
*// This works very well. LineDirection is a made class. Pretty simple to figure out.*
*public void drawLine(Graphics g, LineDirection dir) {*
*if (!dir.isActivated())*
*return;*
*Point[] points = dir.getPoints();*
*Color defaultColor = g.getColor();*
*g.setColor(dir.getColor());*
*for (int i = 1; i < points.length; i++) {*
*int X1 = (int) points[i-1].getX();*
*int Y1 = (int) points[i-1].getY();*
*int X2 = (int) points.getX();*
*int Y2 = (int) points[i].getY();*
g.drawLine((int) X()  +(int)(X1XScale),(int)Y()+ (int)(Y1*YScale* -1),(int) X() +(int)(X2*XScale),(int) Y()+ (int)(Y2*YScale * -1));
g.setColor(defaultColor);
public void drawDefaultGrid(Graphics g) {
g.drawLine(0, Y() , width, Y());
g.drawLine(X(), 0, X(), length);
[http://pastebin.com/Ty9ndCc4]                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       

Answer 1

RedDevil_05 wrote:
[1] For now, I have a line wizard that seperates a algorithm (linear, polynomial only for now) into chunks. How would I go out Parsing it totally from a string, in any format. I need to include such mathmatical operations such as sin( , cos( and ect. I have not even started on a rough draft yet, because I don't know where to start.Here is a thread that may contain your answer: using the [JavaScript Engine|http://forums.sun.com/thread.jspa?threadID=5144807] to evaluate the String containing the expression.
[2] My custom GraphClass is having a hard time repersenting different rates for minium and maxium axis size. For some reason both axis wont draw in the right spot, meaning my X() and Y() are coded wrong. This is some of my code for now:The X axis in Java is just standard increasing to the right and decreasing to the left, therefore, you can easily center by just dividing your maximum X by 2 for a center position. Y on the other hand is going to be a little more difficult, since the Y will be decreasing in the upward direction and increasing downward. You can easily get the center the same way as with the X axis (divid by 2), but then when you plot, you just change the sign on all of your Y coordinates.
I prefer to use a BufferedImage for my graphics, line graphs or custom rendering for games and etc. I can work with that and it will then easily render onto the graphics context of a JPanel.
Hope this help you out.
BTW: your posted code seems to have been gnawed on by an ugly moster or something--it is hideously corrupted, but your link showing your full source shows decent enough code.