The basic construction element to build a formula in SymPy is the symbol. As we saw in the introductory example, a symbol is created by the command symbols. This SymPy command generates symbol objects from a given string:

x, y, mass, torque = symbols('x y mass torque')

It is actually a short form of following command:

symbol_list=[symbols(l) for l in 'x y mass torque'.split()]

followed by a unpacking step to obtain variables:

 x, y, mass, torque = symbol_list

The arguments of the command define the string representation of the symbol. The variable name of the symbol is often chosen identical to its string representation, but this is not required by the language:

row_index=symbols('i',integer=True)
print(row_index**2)  # returns i**2

Here, we also defined that the symbol is assumed to be an integer.

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