MATLAB®

elseif - Execute statements if additional condition is true

Syntax

if expression1, statements1, elseif expression2, statements2, end

Description

if expression1, statements1, elseif expression2, statements2, end evaluates expression1 and, if the evaluation yields logical 1 (true) or a nonzero result, executes one or more MATLAB commands denoted here as statements1. If expression1 is false, MATLAB evaluates the elseif expression, expression2. If expression2 evaluates to true or a nonzero result, executes the commands in statements2.

A true expression has either a logical 1 (true) or nonzero value. For nonscalar expressions, (for example, is matrix A less then matrix B), true means that every element of the resulting matrix has a true or nonzero value.

Expressions usually involve relational operations such as (count < limit) or isreal(A). Simple expressions can be combined by logical operators (&,|,~) into compound expressions such as (count < limit) & ((height - offset) >= 0).

See Program Control Statements in the MATLAB Programming Fundamentals documentation for more information on controlling the flow of your program code.

Remarks

The commands else and if, with a space or line break between them, differ from elseif, with no space. The former introduces a new, nested if that requires a matching end statement. The latter is used in a linear sequence of conditional statements with only one terminating end.

The two segments shown below produce identical results. Exactly one of the four assignments to x is executed, depending upon the values of the three logical expressions, A, B, and C.

if A                           if A
   x = a                           x = a
else                           elseif B
   if B                            x = b
      x = b                    elseif C
   else                            x = c
       if C                    else
          x = c                    x = d
       else                    end
           x = d
       end
   end
end

Examples

Here is an example showing if, else, and elseif.

for m = 1:k
    for n = 1:k
        if m == n
            a(m,n) = 2;
        elseif abs(m-n) == 2
            a(m,n) = 1;
        else
            a(m,n) = 0;
        end
    end
end

For k=5 you get the matrix

a =

     2     0     1     0     0
     0     2     0     1     0
     1     0     2     0     1
     0     1     0     2     0
     0     0     1     0     2

See Also

if, else, end, for, while, switch, break, return, relational operators, logical operators (elementwise and short-circuit)

else

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