# Resolve the Undefined Operator '*' Error for Cell Input Arguments: A Comprehensive Guide

Learn how to fix the undefined operator '*' error for cell input arguments in MATLAB with this comprehensive guide. We will walk you through the step-by-step solution and provide valuable insights into the MATLAB environment, making it easier for you to troubleshoot such errors in the future.

## Introduction

In MATLAB, the `Undefined operator '*' for input arguments of type 'cell'.` error occurs when you try to perform element-wise multiplication on cell arrays. Cell arrays are different from numerical arrays, and therefore, the normal multiplication operator `*` does not work on them. In this guide, we will provide a step-by-step solution to resolve this error and help you understand how to perform element-wise multiplication on cell arrays.

## Prerequisites

To follow along with this guide, you should be familiar with:

• Basic MATLAB commands and syntax
• Creating and manipulating cell arrays in MATLAB

If you need a refresher on these topics, you can refer to the MATLAB documentation.

## Step-by-Step Solution

Understand the error

The first step is to understand why the error is occurring. MATLAB throws this error when you try to use the `*` operator on cell arrays. For example:

``````A = {1, 2; 3, 4};
B = {5, 6; 7, 8};
C = A * B;
``````

This code will result in the error `Undefined operator '*' for input arguments of type 'cell'.` because A and B are cell arrays, not numerical arrays.

Convert cell arrays to numerical arrays

To resolve this error, you must first convert the cell arrays to numerical arrays using the `cell2mat` function.

``````A_num = cell2mat(A);
B_num = cell2mat(B);
``````

Perform element-wise multiplication

After converting the cell arrays to numerical arrays, you can now perform element-wise multiplication using the `.*` operator.

``````C_num = A_num .* B_num;
``````

Convert the result back to a cell array

If you want the result in a cell array format, you can convert the numerical array back to a cell array using the `num2cell` function.

``````C = num2cell(C_num);
``````

Complete code

The complete code to resolve the undefined operator '*' error for cell input arguments is:

``````A = {1, 2; 3, 4};
B = {5, 6; 7, 8};

A_num = cell2mat(A);
B_num = cell2mat(B);

C_num = A_num .* B_num;

C = num2cell(C_num);
``````

## FAQs

### 1. What is the difference between cell arrays and numerical arrays in MATLAB?

Cell arrays in MATLAB are containers for storing data of varying types and sizes. They can hold numbers, strings, structures, or even other cell arrays. Numerical arrays, on the other hand, are matrices or vectors of numbers.

### 2. Can I perform other mathematical operations on cell arrays?

Yes, you can perform other mathematical operations on cell arrays after converting them to numerical arrays using the `cell2mat` function.

### 3. Can I perform matrix multiplication on cell arrays?

Yes, you can perform matrix multiplication on cell arrays after converting them to numerical arrays using the `cell2mat` function. You can then use the `*` operator for matrix multiplication.

### 4. What is the purpose of the `.*` operator in MATLAB?

The `.*` operator in MATLAB is used for element-wise multiplication of two arrays with the same dimensions.

### 5. Is there a way to perform element-wise multiplication on cell arrays without converting them to numerical arrays?

Yes, you can use the `cellfun` function to perform element-wise multiplication on cell arrays without converting them to numerical arrays. The syntax is:

``````C = cellfun(@(x,y) x*y, A, B, 'UniformOutput', false);
``````

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