# What Is a Double Precision Data Type?

//

Heather Bennett

What Is a Double Precision Data Type?

The double precision data type, also known as double, is a commonly used data type in programming languages. It is used to represent floating-point numbers with a higher level of precision compared to the single precision data type.

## Precision in Floating-Point Numbers

Floating-point numbers are used to represent decimal numbers and are commonly used in various applications, such as scientific calculations, financial calculations, and graphical representations. The precision of a floating-point number refers to the number of digits it can represent accurately.

The single precision data type, also known as float, uses 32 bits to store a floating-point number. It can accurately represent about 7 decimal digits. However, for applications that require higher precision, such as simulations or complex mathematical computations, the double precision data type is preferred.

## The Double Precision Data Type

The double precision data type uses 64 bits to store a floating-point number. This allows it to accurately represent about 15 decimal digits. The increased precision provides more accurate results for calculations that involve very large or very small numbers or require high levels of accuracy.

In most programming languages, the double precision data type is denoted by keywords such as `double`, `real`, or `long double`. For example, in C/C++, you can declare a variable of the double precision data type as follows:

• `double myVariable;`

### Precision Comparison: Single vs. Double Precision

To better understand the difference between single and double precision, let’s consider an example:

Suppose we have two variables, `singleNum` and `doubleNum`, both initialized with the value 0.1 and multiplied by 10,000,000:

• `float singleNum = 0.1;`
• `double doubleNum = 0.1;`

If we multiply both variables by 10,000,000, the results will differ:

• Single Precision Calculation:
``float result = singleNum * 10000000;``

In this case, the result will be approximately 999999.94. The limited precision of the single precision data type causes a loss of accuracy.

• Double Precision Calculation:
``double result = doubleNum * 10000000;``

In contrast, the double precision data type can accurately represent the decimal number and yield a result of exactly 1000000.0.

## Conclusion

The double precision data type provides higher precision compared to the single precision data type. It is suitable for applications that require accurate representation and calculations involving large or small numbers. By using double precision, programmers can achieve more precise results in their computations.

In summary, understanding the differences between different data types is crucial for writing efficient and accurate programs.