ENGG 1801 Engineering Computing

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ENGG 1801Engineering Computing

• MATLAB Lecture 3 Revision of Tutorial 3 4
  Concepts, Background for Weeks 5 6 Tutorial,
  Directions for Weeks 7 8 Tutorial
• More Programming in MATLAB

2
Outline of Lecture

• Problem solving revision tutorial 3 4.
• fprintf, printing formats, for tutorial 5 6.
• Getting the most from tutorials.
• New material loops (tutorial 7 8), good
  programming practice.

3
Revision Assigning Variables

• Variables are required to be assigned to carry
  out actions, e.g nTrucks has to be assigned as a
  variable in tut 3, question 1, by gtgt nTrucks
  (something)
• That (something) depends on what you need to do
• if the variable never (or rarely changes, it can
  be typed in directly, gtgt nTrucks 4
• if the variable changes frequently, needs to be
  changed by users, the input function will help to
  prompt the user assign the variable, gtgt nTrucks
  input(How many trucks ? )

4
Revision Functions Punctuation

• Learn about functions by reading the notes,
  coming to lectures.
• Punctuation (like ) is required around text, not
  numbers, e.g. How many trucks?, so the
  following variable is
• a string, gtgt x How many trucks
• a number, gtgt x 433

5
Revision fprintf

• fprintf
• gtgt x 433
• gtgt fprintf(My room is g,x)
• Q Whats with the g?
• A It is a format for output. Here it means
  general output format. Try using gtgt help fprintf
  for some more guidance.

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Examples of Using fprintf
New line

• Printing a line of information
• gtgt fprintf(\nI am talking too much\n)
• To give a number with a decimal point floating
  point format
• gtgt x 42.2
• gtgt fprintf(Load 12.2f N,x)
• Gives
• Load 42.20 N

The printing field is 12 spaces wide, there are
two figures behind the decimalpoint
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Examples of Using fprintf

• Put them together
• gtgt fprintf(\nLoad 12.2f N\n,x)
• prints a line then goes to the next line.
• Several numbers
• gtgt y 3.3
• gtgt fprintf(\nLoad 12.2f N \nDeflection
  6.2f mm\n,x,y)
• Load 42.20 N
• Deflection 3.30 mm

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Examples of Using fprintf

• Scientific notation exponential format
• gtgt fprintf(\n Load 12.2e N \n Deflection
  6.2f mm \n,x,y)
• Load 4.22E001 N
• Deflection 3.30 mm
• Useful formats for tutorials in weeks 5 6, 7
  8 and onwards, are e, f, \n

The E001 takes up 5 spaces, there are two
numbers behind the decimal point
9
Getting the Most from Tutorials

• Ask the tutors to check your answers dont get
  bogged down or be misled by wrong answers to
  early questions.
• Dont copy the work of others or just leave this
  is not ethical, good practice, does not help you
  to learn.
• Read the lecture notes prior to the tutorial.

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Loops

• When you want to do something several times, in
  succession.
• gtgt for numb 1 3
• gtgt fprintf(Case 5.0f \n, numb)
• gtgt end
• Case 1
• Case 2
• Case 3

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Loops

• Notice that good programming practice involves
  indenting material within FOR END loops and IF
  ELSEIF ELSE ... END decisions for better
  readability.
• FOR END, is capped off by an end statement
• Read notes (or Help) on loops using WHILE END

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Conclusions

• We are now learning more about programming
  practice useful tools for this.
• Have reviewed
• Assigning variables.
• Functions punctuation.
• fprintf formatting.
• Getting the most from tutorials.
• Extending decisions (IF ELSE IF ELSE END)
  to loops (FOR END).