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Cell[CellGroupData[{
Cell["3. Defining Variables and Functions", "Title",
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In this section we cover various ways to store a value or an \
expression in a variable (a place inside the computer) as well as ways to \
store a list of instructions inside a function.\
\>", "Text",
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"We have already learned how to give a value a name: we decide on a \
consecutive sequence of letters (the \"name\"), follow it by a single equals \
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in a little more detail. When we give Mathematica an instruction such as \"",
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"the right-hand side of the expression (yielding an Integer, 7). Then \
Mathematica",
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" a new variable (by which we mean that Mathematica will remember from now \
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" of our operation is whatever value was assigned, in this case 7, so \
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"All of the operators which we have seen have special functional forms. \
Here is a list of the operators, together with their functional forms:\n\n",
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Once a variable, or any name, is declared and initialized, it may \
be redefined or reassigned. Once we do so, Mathematica essentially forgets \
the first value, and from that point forward until another redefinition, the \
name will refer to the new value.\
\>", "Text",
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"\" will then refer to the value 9, of Integer type. Although this is the \
desired behavior, here is a caveat: if we return to an earlier cell in our \
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"Frequently we will want to take a variable's value, do something simple to \
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mess = 10;
mess = mess + 10\
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Here are some more examples of arithmetic value modification:\
\>",
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Of course, if we wish to assign a value to a variable based on \
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"One very common way in which computer programmers change values of \
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