Logical Vectors

1
Logical Vectors
2
Using Logical Operators

• Draw the sine curve from -270 to 270 degree with
  only the positive part
• Draw the plot for sin(x)/x from -270 to 270
  degrees
• Draw the tangent curve from -270 to 270 degree
• In a random number generator from 0 to 10, how
  many numbers would be gt 5 on average
• What is the chance of getting six after rolling
  a well balanced die

3
Precedence of Operators

• ()
• (unary) -(unray)
• /
• (binary) -(binary)
• gt lt gt lt

4
Precedence of Operators

• What will be the output
• 3gt 1 0
• 1 lt rlt 5
• a gt b
• a gt b
• (a gt b)

5
Logical Vectors

• We learnt that indices of vectors can be
  subscripted
• a-2 0 1 5 9 a(5 1 3)
• We can use logical vectors to obtain values at
  indices
• a(logical( 0 1 0 1 0)
• Remove all elements in a are that are greater
  than zero

6
Logical Functions

• islogical
• Returns 1 if it is a logical vector
• any
• Returns 1 if any element of a is non-zero
• all
• Returns 1 if all elements of a are non-zero
• exist
• Returns 1 is a is a vraibel defined in
  workspace
• find
• Returns a vector with indices that match given
  condition
• isempty
• Returns 1 if array a is empty

7
Using Logical Functions

• Given the temperatures of the week in an array,
• Find which day was the hottest
• Check if there was a day when the temperature was
  below 0 degree celcius
• Was there any day where the temperature was below
  -10 degree celcius
• Logical vectors and functions make shorter codes

8
Summary

• What we learned
• Sections covered
• All of chapter 5