learningMatlab

Simple commands

Play around with the following commands just to get a feel for the command prompt, what error messages look like, etc.
Keep notes on anything that you find surprising or that you don’t understand.

Useful operators, commands, and concepts for this unit…

pi, ( ), [ ] :, whos, size(), rand(), mean(), std(), min(), max(), rem() (remainder after division), reshape(), repmat(), indexing, rows, columns

Make sure to clear all before starting on these exercises. Keep some notes on what’s going on and try to understand each step and then move on to the next section
```
  a = [3, pi, 10, 1; 2 7 4 1]
  b = 20:3:30
  c = 2
```

Is the following allowed (correct syntactically)? Why?:

  a .* c
  a .* b
  b .* c
  d = a .* c

Given the variables a, b, c, d, what about the following. Some of these are quite subtle, so make sure you understand:

  % indexing into a
  a(:,2)
  a(1,4)
  a(1)
  a(2)
  a(9)
  a(4,4)
  a(4,4) = 1.2
  a
  % ... and b
  b(3,1)
  b(1,3)

Moving on to slightly larger vectors and matrices:

  % spot the difference here:
  e = rand(100,1)
  e = rand(100,1);
  % now that we have this:
  mean(e)

… and now for matrices:

  a
  mean(a)
  mean(a,1)
  mean(a,2)
  help mean

Other useful functions that “collapse across dimensions”:
```
  median(e)
  std(e)
  max(e)
  min(e)
```
… and we can also keep track of where the min/max occurred:
```
  [minValue minIndex] = min(e)
  e(minIndex)
```
… and some others that are useful with dealing with indices, counting, etc.:
```
  f = 1:100
  rem(f,2) % remainder after division w/ 2
```
Not standard Matlab, but very useful helper functions from @justingardner
```
  isodd(f)
  iseven(f)
```
See how you can turn 1..N into a repeating pattern:
```
  rem(f,3) + 1
  rem(f+2,3) + 1
```

Turn a vector into a matrix by reshape():

  size(f)
  reshape(f,[10 10])
  reshape(f,[2 50])
  reshape(f,[2 40])

Creating bigger vectors and matrices from smaller ones by tiling: repmat():
```
  repmat([1 2 3], 1, 5)
  repmat([1 2 3], 5, 1)
```

More simple commands and some practice making vectors and matrices that contain specific things.

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learningMatlab

Simple commands

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