If the argument is not factorable, the original input argument will be returned unmodified. The expand function will multiply out terms and factor will do the reverse: The collect function collects coefficients, such as the following: The functions collect, expand, and factor work with polynomial expressions. Not all expressions can be simplified, but the simplify function does whatever it can to simplify expressions, including gathering like terms. There are several functions that work with symbolic expressions and simplify the terms. For example:Ģ 0 -1 0 5 14.6.2 Simplification Functions The built-in functions sym2poly and poly2sym convert from symbolic expressions to polynomial vectors and vice versa.
If using multiple variables as symbolic variable names is desired, the syms function is a shortcut instead of using sym repeatedly. If, however, z is a symbolic variable to begin with, quotes are not needed around the expression, and the terms are automatically collected: The following creates a symbolic expression by passing a string, but the terms are not collected automatically.
It can be seen from the last example that MATLAB will collect like terms in these expressions, adding the x 2 and 4 x 2 to result in 5 x 2. For example, the variables b and c store symbolic expressions:Īll basic mathematical operations can be performed on symbolic variables and expressions (e.g., add, subtract, multiply, divide, and raise to a power, etc.). Symbolic variables can also store expressions. For example, to create a symbolic variable a and perform the addition just described, a symbolic variable would first be created by passing the string ‘ a’ to the sym function: MATLAB has a type called sym for symbolic variables and expressions these work with strings. 14.6.1 Symbolic Variables and Expressions (Therefore, this may or may not be part of your own system.) Symbolic Math Toolbox includes an alternative method for solving equations, and is therefore covered in this chapter. Toolboxes contain related functions and are add-ons to MATLAB. The symbolic math functions are in Symbolic Math Toolbox in MATLAB. Symbolic mathematics means doing mathematics on symbols (not numbers!). Stormy Attaway, in Matlab (Fourth Edition), 2017 14.6 Symbolic Mathematics
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