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Operations and Expressions

An m-file environment has all of the standard arithmetic operations (addition, subtraction, etc.) and functions (sine, cosine, logarithm, etc.). Table 1 lists the most commonly used operations; in this table, x and y are scalars. (A scalar is a single value, as opposed to a vector or matrix which consists of many values.)

Some Common Scalar Mathematical Operations.
Operation m-file
x - y
x - y
x + y
x + y
xy
x*y
\tfrac{x}{y}
x/y
x^y
x^y
e^x
exp(x)
\log_{10}(x)
log10(x)
\ln(x)
log(x)
\log_2(x)
log2(x)
\cos(x)
cos(x)
\sin(x)
sin(x)
\sqrt{x}
sqrt(x)

Expressions are formed from numbers, variables, and these perations. The operations have different precedences. The

^

operation has the highest precedence;

^

operations are evaluated before any other operations. Multiplication and division have the next highest precedence, and addition and subtraction have the lowest precedence. Precedence is altered by parentheses; expressions within parentheses are evaluated before expressions outside parentheses.

Example 1

Table 2 below shows several mathematical formulas, the corresponding expressions, and the values that are computed for the expressions.

Example Expressions
formula MATLAB Expression Computed Value
5^2 + 4^2
5^2+4^2
41
(5 + 4)^2
(5+4)^2
81
\tfrac{2+3}{4-5}
(2 + 3)/(4 - 5)
\log_{10}(100)
log10(100)
2
\ln(4(2 + 3))
log(4*(2 + 3))
2.9957

Useful Tricks

These tricks are occasionally useful, especially when you begin programming with m-files.

  • A semicolon added at the end of a line suppresses the output.
  • Often it is useful to split input over multiple lines. To split a statement across multiple lines, enter three periods ... at the end of the line to indicate it continues on the next line.

Example 2

You could split the expression \tfrac{2+3}{4-5} over multiple lines as follows:
(2+3)...
/(4-5)

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