qat.core.variables

`qat.core.variables.ArithExpression`	Represents arithmetic expressions
`qat.core.variables.Symbol`	Describes a given label in the AST on an `ArithExpression`

This framework provides a set of symbols:

`qat.core.variables.abso()`	Absolute value of a (complex) number
`qat.core.variables.angle()`	Angle in the complex plane of a complex number
`qat.core.variables.atan2()`	The atan2 function from the math library
`qat.core.variables.cos()`	Cosinus function
`qat.core.variables.exp()`	Natural exponential function
`qat.core.variables.get_item()`	A function extracting a number by its position in an array
`qat.core.variables.heaviside()`	Heaviside function
`qat.core.variables.imag()`	Imaginary part extraction function
`qat.core.variables.ln()`	Natural logarithm function
`qat.core.variables.real()`	Real part extraction function
`qat.core.variables.sin()`	Sinus function
`qat.core.variables.sqrt()`	Square root function
`qat.core.variables.vmax()`	Maximum of two numbers

User defined symbols can be created using the class Symbol. For instance, the following piece of code adds a new symbol that represents the min between two numeric values.

from qat.core.variables import Variable, Symbol

# token will "min"
# underlying function is the standard `min`
# it has arity 2
# it is not an infix operator
my_min = Symbol("min", min, 2, infix=False)

a, b = Variable("a"), Variable("b")

expr = my_min(a, b)
print(expr)
print(expr(a=3))
print(expr(a=3, b=4))

min(a,b)
min(3,b)
3

Warning

If you create a Symbol in your environment, but choose to send it for evaluation to a remote Qaptiva appliance, the remote environment will not be aware of this new Symbol and the expression evaluation might fail.