About GC (compilerabuse.com)

You can use this program for building two-dimensional graphs of functions. In order to draw a graph of a function, enter the function into the upper box of the window and press Apply/Draw or Enter. Use letter ‘x’ as an argument. All the functions you enter will be added to the list box that is on top of the window. You can then scroll through the list and select a function. After you select a function, press Apply/Draw or Enter. The function you have selected will become current and will be drawn in blue. All other functions in the list will be drawn in green. Also, the function that is current will be calculated at the value that is shown in the x= box. The result will be displayed in the f(…)= box. You can add the values of x into the x= list the same way you add functions to the f(x)= list. Just press Apply/Draw or Enter every time you change or add values into those boxes. Pressing the Remove button will delete the current function from the list and its graph from the display window. The last function in the list will become current. Pressing Clear Argument List will remove all the values from the x= list except for ‘0’. Clear All clears both function and argument lists, and the display window. All the buttons on the window have corresponding items in the menu.

In the boxes that are in the lower right corner of the window you can enter the intervals, at which you want to view the graphs, that is the x and y upper and lower limits. You can also use the arrow buttons to shift the view (Shift mode). Using the arrow buttons in Expand mode will expand the limit corresponding to the Arrow button you are pressing without changing other limits. Pressing Zoom in button proportionally increases both upper limits, and decreases the lower ones. Pressing Zoom out does the opposite. Set Default inserts default values for the x and y limits. The default values are x: [-5; 5], y: [-5; 5]. You don’t have to press Apply/Draw after pressing these buttons; the graphs will be redrawn automatically.

The following tokens in function expressions are recognized by the program and are evaluated in the following order:

1	Numbers and variables	2; .6775; x; pi (3.1415…)	These carry numerical values and are evaluated first.
2	Expressions in Parentheses	(x); [5x-2]
3	Default Multiplication!	3x=3x; pix=pix xcos x=x(cos(x)) 3x^2=(3x)^2 *3x^2*=3(x^2)	Expressions where multiplication is implied, but multiplication sign (*) is omitted are evaluated before most other expressions.
4	Power	x^2; 3^(x-4)
5	Unary +, -, /, and Algebraic and Trigonometric Functions (parentheses are not necessary but always safe)	+8; -7.25; /3x=1/(3*x)	Expression that have a division sign but no numerator are evaluated as if the numerator is 1.
5		abs x exp x sqrt x log x ln x sin x cos x sec x cosec x tan x ctg x asin x acos x atan x actg x	Absolute value. Exponent (e=2.71…) to the power of x. Square root of x. Base 10 logarithm of x. Natural (base e) logarithm of x. Sine of x. Cosine of x. Secant of x. Cosecant of x. Tangent of x. Cotangent of x. Arcsine of x. Arccosine of x. Arctangent of x. Arccotangent of x.
6	Binary * and /	2*x; x/(x-8)	Ordinary multiplication and division.
7	Binary + and -	5.45+x; x-pi	Ordinary addition and subtraction.