# Matlab help with if conditional

• MATLAB
• astronut555
In summary, the conversation discussed the use of an if statement without a condition to test. It was explained that the "if" command in Matlab can also be based on a true or false value, represented by 1 or 0. It was suggested that the code may have initially had a condition such as x>0, but it was later changed to 0 to prevent the plot command from executing. This could have been done during debugging and the code was not removed afterwards, making it easy to reactivate the plot by changing one character.
astronut555
Hello all,

I'm reading through some code that someone else wrote and have come across the following conditional:

if 0

figure; plot(times, average);

end;

I've never seen if used without a statement to test (ie: if x>0...) and I can't find any documentation on it anywhere.

Anyone seen this before and know what it does?

Thanks!

Matlab's "if" command bases its decision on whether the next object is true or false, and this can be expressed also by 1 or 0. You are used to seeing an expression such as x>0, but this will evaluate to either true/1 (if the condition is true) or false/0 (otherwise). Your code might have had such a test at one time but it was replaced by 0 to force the plot command not to execute. Its possible the programmer added this plot during debug with a 1, then changed it to 0 when debug was over instead of removing the code. That way he/she can always reactivate the plot by changing one character.

makes sense, thanks!

## 1. What is the syntax for creating an if statement in Matlab?

The syntax for creating an if statement in Matlab is as follows:
if condition
statements
end
The condition is a logical expression that evaluates to either true or false, and the statements are executed only if the condition is true.

## 2. Can an if statement have multiple conditions in Matlab?

Yes, an if statement in Matlab can have multiple conditions using the && (logical AND) or || (logical OR) operators. For example:
if (x > 0 && y < 10)
statements
end
This will execute the statements only if both conditions, x > 0 and y < 10, are true.

## 3. How do I use an else statement in Matlab?

The else statement is used in conjunction with an if statement to execute a different set of statements when the condition is false. The syntax for an if-else statement in Matlab is:
if condition
statements
else
statements
end
The statements within the "else" block will be executed when the condition is false.

## 4. Can I nest if statements in Matlab?

Yes, if statements can be nested within each other in Matlab. This means that an if statement can contain another if statement within its statements block. However, it is important to keep track of the number of "end" statements to avoid syntax errors.

## 5. How do I use the elseif statement in Matlab?

The elseif statement is used to check for multiple conditions in an if statement. It is placed between the if and else blocks and will only be executed if the previous condition was false. The syntax for using an elseif statement in Matlab is:
if condition1
statements
elseif condition2
statements
else
statements
end
The elseif statement can be used multiple times within an if statement to check for different conditions.

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