Equation Grapher (Flash Version)
Enter an Equation using the variables x and/or y and an =, press Go:
Description
It can plot an equation where x and y are related somehow (not just y=...), like these:
Examples:
 x^2+y^2=9 (an equation of a circle with a radius of 3)
 sin(x)+cos(y)=0.5
 2x3y=1
 cos(x^2)=y
 (x3)(x+3)=y^2
 y=x^2
If you don't include an equals sign, it will assume you mean "=0"
It has not been well tested, so have fun with it, but don't trust it.
If it gives you problems, let me know.
Note: it can take a few seconds to finish, because it has to do lots of calculations.
If you just want to graph a function in "y=..." style you may prefer Function Grapher and Calculator
Zooming
To zoom into an area, select an area with the mouse (click, hold down and drag, then release). The area you selected will be the new bounds.
If you just clickandrelease (without creating a rectangle), then the spot you clicked on will be the new center
You can zoom out using the Out 2X or Out 10x button.
To reset the zoom to the original bounds click on the Reset button.
Plot StylesAs well as the usual curve produced by Fast or Detailed:


You can also have shaded plots of how far the value of the left hand side of the equation is from the right hand side: 

Or how near they are (very handy for finding where the equation may be true but the grapher just misses): 

And there is also an option for the slope of the equation: This option takes a little longer to run (lots of calcs to do). When the slope is large it shows as green.

The usual thing applies: these are all plotted using computer calculations. Roundoff can cause errors or values can be missed completely.
All Functions
Operators
+  Addition operator  

  Subtraction operator  
*  Multiplication operator  
/  Division operator  
^  Exponent (Power) operator 
Functions
sqrt  Square Root of a value or expression.  

sin  sine of a value or expression  
cos  cosine of a value or expression  
tan  tangent of a value or expression  
asin  inverse sine (arcsine) of a value or expression  
acos  inverse cosine (arccos) of a value or expression  
atan  inverse tangent (arctangent) of a value or expression  
sinh  Hyperbolic sine (sinh) of a value or expression  
cosh  Hyperbolic cosine (cosh) of a value or expression  
tanh  Hyperbolic tangent (tanh) of a value or expression  
exp  e (the Euler Constant) raised to the power of a value or expression  
ln  The natural logarithm of a value or expression  
log  The base10 logarithm of a value or expression  
floor  Returns the largest (closest to positive infinity) value that is not greater than the argument and is equal to a mathematical integer.  
ceil  Returns the smallest (closest to negative infinity) value that is not less than the argument and is equal to a mathematical integer.  
round  Round to the nearest integer. Examples: round(2.5) = 2, round(0.1) = 0, round(0.1) = 0, round(2.5) = 3  
abs  Absolute value (distance from zero) of a value or expression  
sign  Sign (+1 or 1) of a value or expression  
Constants
pi  The constant π (3.141592654...)  

e  Euler's number (2.71828...), the base for the natural logarithm 