SymPy function or method Description Example; symbols() create symbolic math variables: x, y = symbols('x y').subs() substitute a value into a symbolic math expression: expr.subs(x,2).evalf() evaluate a symbolic math expression as a floating point number: expr.evalf() Like in Numpy, they are typically built rather than passed to an explicit constructor. This includes named functions like cos(x) and log(x) as well as undefined functions like f(x). array ( np . The simplest kind of expression is the symbol. Sympy's core object is the expression. You can rate examples to help us improve the quality of examples. These output objects are separated by commas with no quotation marks. I'm trying to convert output of a cubic equation to a function outside of sympy. Symbolic to Numerical Functions¶ You can turn sympy functions into lambda functions that are compatible with numpy using lambdify : f = sym . The output of the symbols() function are SymPy symbols objects. As mentioned earlier, symbolic computations are done with symbols. Python Function - 18 examples found. sympy.core.sympify.sympify() is the function that converts Python objects such as int(1) into SymPy objects such as Integer(1). In [2]: x, y = symbols ('x y') Now that the symbols x and y are instantiated, a symbolic math expression using x and y can be created. It exports all latin and greek letters as Symbols, so we can conveniently use them. The Function class is a subclass of Expr, which makes it easier to define mathematical functions called with arguments. from import x, y Symbols can be imported from the module. a = Symbol('a') b = Symbol('b') They can be defined with Symbol. It is a base class for all applied mathematical functions, as also a constructor for undefined function classes. Symbol() function's argument is a string containing symbol which can be assigned to a variable. Subclasses of Function should define a class method eval, which returns a canonical form of the function application (usually an instance of some other class, i.e. SymPy provides Eq() function to set up an equation. The programs shows three ways to define symbols in SymPy. These are the top rated real world Python examples of sympy.Function extracted from open source projects. Sympy has a quick interface to symbols for upper and lowercase roman and greek letters: sin ( x ) g = sym . Functions . linspace ( 0 , 1 , 10 ))) Following categories of functions are inherited from Function class − import sympy as sp u, x, y = sp.symbols('u x y') eq = - y - sp.Integral(x**2, (x, 1, u)) solved = sp.solveset(eq.doit(), u, domain=sp.S.Reals) lam = sp.lambdify(y, sp.solveset(eq.doit(), u, domain=sp.S.Reals)) Symbol is the most important class in symPy library. SymPy variables are objects of Symbols class. It also converts the string form of an expression into a SymPy expression, like sympify("x**2") -> Symbol("x")**2 . Sympy package has Function class, which is defined in sympy.core.function module. Since the symbols = and == are defined as assignment and equality operators in Python, they cannot be used to formulate symbolic equations. lambdify ( x , f , 'numpy' ) g ( np . SymPy - Symbols.