Another use of the term virtual machine is that by IBM, whose VM operating system provides each user
the illusion of having a complete IBM 370 machine for their personal use.
PROCEDURAL PROGRAMMING
For many new programmers, procedural programming is the natural paradigm. A program can often be
conceived simply as a list of instructions to be executed in order; that is, a procedure to be followed by the
computer. Procedural programming languages are also called imperative languages.
CHAP. 4] SOFTWARE 49
In procedural programming, the code for a specific job is contained in a named procedure. Another name
for a procedure is often subroutine. For instance, one might create a procedure to find the standard deviation of
an array of numbers.
The standard deviation of a measure is defined as the square root of the average squared deviation from the
mean. Here ??is the population standard deviation, and ?µ is the population mean:
(4.1)
If one is working from a sample and intending to infer the standard deviation of the larger population, the
best estimate will be obtained by dividing the sum of deviations by (n??’1) instead of n. Here s is the sample standard
deviation, and is the sample mean:
(4.2)
An equivalent formula often useful for computation is the following:
(4.
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