If-Else in MATLAB: if, elseif, else Syntax with Examples

An if-else in MATLAB is written if, elseif, else, end. The branch runs only when its condition is true, and elseif is one word: writing else if with a space opens a second, nested if that needs its own end. This page is for researchers and analysts who need to branch on data (thresholds, missing values, string options) and want the array-condition and operator rules that most short answers skip.

What it is used for in research

Conditional statements let a script choose what to do depending on the data in front of it. Typical research uses are applying a different processing step above or below a threshold, skipping a file whose dimensions do not match the others, and selecting an analysis path from a text option. Repeating a step over many files or samples is the job of a loop; see loops in MATLAB and combine the two when each iteration needs a decision.

Install or access (official source only)

MATLAB is a commercial product from MathWorks, available through mathworks.com or through your institution’s MathWorks account if it has one. The if statement is part of the core MATLAB language, so no toolbox is needed. For a wider orientation to the product, see what MATLAB is used for.

Step-by-step: write an if, elseif, else block

1. Use the documented syntax

The MathWorks reference gives this form. elseif and else are optional, and you can use several elseif branches.

if expression
    statements
elseif expression
    statements
else
    statements
end

2. Run a first example

x = 7;
if x < 0
    disp('negative')
elseif x == 0
    disp('zero')
else
    disp('positive')
end

MATLAB tests the conditions from the top and runs only the first branch whose condition is true. Here x < 0 and x == 0 are false, so the else branch prints positive.

3. Combine conditions with && and ||

MathWorks advises using && and || inside if conditions, not & and |. Inside an if condition the single-character forms short-circuit like the double forms, but the double forms make the intent consistent. The documentation’s range check has this shape:

if (x >= minVal) && (x <= maxVal)
    disp('x is in range')
end

Short-circuiting also lets you guard a second test that would fail if the first is false. The documentation’s example only calls myfunction if the file exists:

x = 42;
if exist('myfunction.m','file') && (myfunction(x) >= pi)
    disp('Expressions are true')
end

“elseif” versus “else if”, the common pitfall

Both MATLAB and GNU Octave document this: elseif is one keyword. With a space, the second if is nested inside the else branch, and every if needs its own end. The Octave manual adds that elseif “must not be spelled else if” and warns that, when run from a file, the mismatch can produce errors or wrong results.

if x < 0
    disp('negative')
elseif x == 0
    disp('zero')
else
    disp('positive')
end

if x < 0
    disp('negative')
else if x == 0
    disp('zero')
else
    disp('positive')
end
end

Prefer the first form. It stays flat however many branches you add, and the number of end keywords stays at one.

Output and how to read it

An if block produces no output of its own; what you see is whatever the executed branch does, such as a disp call or an assignment. If nothing appears, no condition was true and there was no else. To see which branch ran, add a disp or fprintf call in each branch while debugging.

Array conditions: what “true” means

Per the MathWorks reference, an expression is true when its result is nonempty and contains only nonzero elements; otherwise it is false. Two consequences matter for data analysis.

A comparison on an array is true only if every element passes

Wrap the comparison in any to test whether at least one element passes, or in all to make the every-element rule explicit.

signal = [0.2 0.9 0.4];
limit = 0.8;
if any(signal > limit)
    disp('At least one sample exceeds the limit')
else
    disp('All samples are within the limit')
end

Here signal > limit is [0 1 0]. Used directly it would be false because not all elements are nonzero, while any returns true and the first branch runs. For more on the arrays being tested, see matrices in MATLAB.

An empty result is false

If a condition evaluates to an empty array, the branch does not run and no error is raised. That can hide a mistake such as a filter that matched no rows, so check isempty explicitly when emptiness is meaningful.

Comparing text and whole arrays

Do not use == for these cases. The MathWorks reference states that == on character vectors of different sizes results in an error, and that it errors on arrays of different sizes.

• Character vectors: use strcmp(reply,'y').
• Whole arrays: use isequal, for example if isequal(size(A),size(B)) before concatenating A and B.
• Not equal: use ~= for numeric comparison.

Alternatives inside MATLAB

The documentation notes that logical indexing is often faster than an if inside a loop, so for “apply to every element above a threshold” prefer an index such as signal(signal > limit) = limit; over looping with a conditional. When one variable selects among many discrete values, a switch statement can be clearer than a long elseif chain. If you wrap a conditional in a small function, see anonymous functions in MATLAB.

Troubleshooting

Free alternatives

FAQ

What is the syntax for if else if in MATLAB?

Write if condition, then elseif condition, then optionally else, and finish with a single end. You can include several elseif branches.

Is it “else if” or “elseif” in MATLAB?

It is elseif, one word. else if with a space starts a nested if that requires its own end.

How do I test two conditions at once?

Join them with && for “and” or || for “or”, which MathWorks recommends in if conditions.

Why does my if on an array not run?

A condition on an array is true only when the result is nonempty and every element is nonzero. Use any or all to state what you mean.

Can I use if-else in a loop?

Yes. Put the conditional inside the loop body. If the loop only applies a threshold, logical indexing may be simpler and faster, per the MathWorks documentation. See loops in MATLAB.

Sources

• MathWorks, if, elseif, else (MATLAB documentation), read 2026-11-07.
• GNU Octave manual, The if Statement, read 2026-11-07.
• Python Software Foundation, The Python Tutorial, More Control Flow Tools, read 2026-11-07.