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How to Sum Vectors in MATLAB?

Published in MATLAB Vector Operations 2 mins read

In MATLAB, you can easily sum the elements of a vector using the built-in sum function.

The most straightforward way to sum the elements of a vector in MATLAB is by using the sum function. According to the documentation, the syntax S = sum(A) returns the sum of the elements of A. If A is a vector, then sum(A) returns the sum of the elements. This is the primary method you will use for vector summation.

Using the sum() Function

The sum() function is specifically designed for this purpose. When you pass a vector to sum(), it calculates and returns the total sum of all numbers within that vector.

Syntax

The basic syntax is:

S = sum(vectorName)

Where:

  • vectorName is the name of the MATLAB variable holding your vector.
  • S is a variable that will store the resulting sum.

Examples

Let's look at a few examples to illustrate how this works.

Example 1: Summing a Row Vector

Suppose you have a row vector v1.

v1 = [1 2 3 4 5];
total_sum_v1 = sum(v1);

In this case, total_sum_v1 will be 1 + 2 + 3 + 4 + 5, which equals 15.

Example 2: Summing a Column Vector

The sum() function works identically for column vectors.

v2 = [10; 20; 30]; % A column vector
total_sum_v2 = sum(v2);

Here, total_sum_v2 will be 10 + 20 + 30, resulting in 60.

Example 3: Summing a Vector with Negative Numbers

The function correctly handles negative values.

v3 = [-1 -2 5 10];
total_sum_v3 = sum(v3);

total_sum_v3 will be -1 + -2 + 5 + 10, which sums up to 12.

Practical Considerations

  • Data Types: The sum function generally handles standard numeric data types (double, single, integers). The output data type usually matches the input, but for integer types, the sum might be accumulated in a wider type to prevent overflow.
  • Empty Vectors: If you call sum() on an empty vector (e.g., []), it will return 0.

In summary, to sum the elements of any vector in MATLAB, simply use the sum(vector) command. This utilizes the built-in functionality described, where sum(A) returns the sum of the elements when A is a vector.

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