E77: INTRODUCTION TO COMPUTER PROGRAMMING FOR SCIENTISTS AND ENGINEERS

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E77 INTRODUCTION TO COMPUTER PROGRAMMING FOR
SCIENTISTS AND ENGINEERS

• Lecture Outline
• 1. Two-dimensional arrays revisited
• 2. String arrays
• 3. Cell arrays

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Two-dimensional arrays revisited

• 1. Two-dimensional arrays revisited
• Two-dimensional simple arrays consist of m rows
  and n
• columns of real numbers. For example
• The two-dimensional array A consists of m 2
  rows and
• n 3 columns.
• All rows (respectively, columns) in a simple
  array contain
• the same number of elements.

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Two-dimensional arrays revisited

• Important operations on two-dimensional arrays
  include
• Input and output
• Indexing and sizing
• Scalar and element-wise addition, multiplication,
  etc.
• Addition, deletion and redefinition of rows or
  columns
• Reshaping
• Contents analysis (sort, sum, find
  maximum/minimum)

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Two-dimensional arrays revisited

• Example
• Weigh homework, midterm and final exam grades
• appropriately to obtain the final numerical mark
  for a group
• of students registered in a course.
• Weights homework 35, midterms 40, final 25

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String arrays

• 2. String arrays
• Two-dimensional string arrays are simple
  two-dimensional
• arrays of character strings. For example
• What is the dimension of the Football_score
  array?
• The symbols 14 and 41 are input as strings, not
  numbers.
• String arrays are of limited use. Why?

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Cell arrays

• 3. Cell arrays
• A cell array is a data type which permits the
  grouping of
• dissimilar elements (themselves arrays) into a
  single variable.
• Cell arrays are a very powerful tool for data
  management.

A cell
A string
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Cell arrays

• Main operations involving cell arrays
• Input and indexing (parentheses vs. curly
  brackets)
• ( ) to identify a cell (but not its contents)
• to define the contents of a cell
• Display of cell contents (celldisp, cellplot)
• Generation of empty cell arrays (cell)
• Concatenation and extraction of sub-arrays of a
  cell
• array

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Summary

• What did we learn today?
• Two-dimensional simple arrays are easy to
  manipulate
• in MATLAB and can be used to store arithmetic
  and
• string information.
• String arrays are not very flexible.
• It is possible to store arithmetic and string
  data of
• differing sizes in cell arrays.
• In cell arrays, one needs to distinguish between
  cell
• indexing (which cell?) and content indexing
  (what is
• the content of a cell?).