The graphing App will accept any of the following functions (use the notation shown):

Straight lines: (like 3x - 2)
Polynomials: (like x^3 + 3x^2 - 5x + 2)
Any of the trigonometric functions: sin(x), cos(x/2), tan(2x), csc(3x), sec(x/4), cot(x)
The inverse trigonometric functions: arcsin(x), arccos(x), arctan(x), arccsc(x), arcsec(x), arccot(x)
Exponential (e^x) and logarithm (ln(x) for natural log. For log base 10 you need to put ln(x)/ln(10). I'm using Change of Base rule.)
Absolute value: use "abs" like this: abs(x)
The hyperbolic functions and their inverses: sinh(x), cosh(x), tanh(x), arcsinh(x), arccosh(x), arctanh(x)
Sign (returns 1 if the sign of the function value is positive, -1 if the sign of the function is negative. For example, try sign(sin(x)))