Matlab Array - Creating

Creating

• The methods below create new arrays directly; they do not include constructing a new array by combining, concatenating, or slicing an existing one.

Direct Construction

Use square brackets [] together with commas , (or spaces) and semicolons ;:

• List all elements inside []
• Within a row, separate elements with , or whitespace
• Separate rows with ;

Row Vectors

• Arithmetic sequences
  • Operator :: <[start:<step>:end]>
    • All three operands are double
    • step defaults to 1
    • end need not be ≥ start; in that case step must be negative, otherwise the result is empty
    • The first element of the result is start; the last is start + floor((end - start) / step) * step
  • Function linspace
• Geometric sequences
  • Function logspace

Column Vectors

• Transpose operator '

2-D Arrays

A = [1 2 3; 2 5 6; 1 4 5];
B = [1:5; linspace(3, 10, 5); 3 5 2 6 4];
C = [[1:3]' linspace(2, 3, 3)' [3 5 6]'];

Special Arrays

• Zero array: function Matlab Functions - zeros
• Ones array: functionones
  • Same syntax as zeros, with 0 replaced by 1
• Identity array: functioneye
  • Same syntax as zeros; 1 on the main diagonal, 0 elsewhere
  • Cannot create N-D (more than 2-D) arrays
• Uniformly distributed random array: functionrand
  • Same syntax as zeros, with 0 replaced by samples drawn uniformly on $[0,1]$
  • However,typename may only besingle ordouble
• Normally distributed random array: functionrandn
  • Same asrand, with the uniform distribution on $[0,1]$ replaced by the standard normal distribution on $\mathbb{R}$
• Logical array: functionstrue andfalse
  • Same syntax as zeros, with 0 replaced by logical 1/0; produces a logical array
  • Therefore there is notypename parameter
• Diagonal array: function diag
• Magic square: function magic