Python math.erf() Method

---

---

The Python math.erf() method is used to calculate the error method. It is a mathematical method that describes the probability of an event occurring within a certain range of values in a normal distribution.

Mathematically, the error method is defined as −

$$\mathrm{erf(x)\:=\:\frac{2}{\sqrt{\pi}}\:\int^{x}_{0}\:e^{−t^{2}}\:dt}$$

Where, e is the base of the natural logarithm and π is the mathematical constant pi. The error method is an odd method, meaning that erf(-x) = -erf(x) and is being bounded between -1 and 1.

Syntax

Following is the basic syntax of the Python math.erf() method −

math.erf(x)

Parameters

This method accepts a real number or a numeric expression as a parameter for which you want to calculate the error method.

Return Value

The method returns the value of the error method evaluated at x.

Example 1

In the following example, we are calculating the error method for a positive real number using the math.erf() method −

import math
x = 1.5
result = math.erf(x)
print("Error method for x =", x, ":", result)

Output

The output obtained is as follows −

Error method for x = 1.5 : 0.9661051464753108

Example 2

In here, we are calculating the error method for a negative real number using the math.erf() method −

import math
x = -0.75
result = math.erf(x)
print("Error method for x =", x, ":", result)

Output

Following is the output of the above code −

Error method for x = -0.75 : -0.7111556336535151

Example 3

In this example, we are evaluating the sum of error methods for x=2 and x/2 using the math.erf() method−

import math
x = 2
result = math.erf(x) + math.erf(x/2)
print("Error method expression result for x =", x, ":", result) 

Output

We get the output as shown below −

Error method expression result for x = 2 : 1.8380230579686676

Example 4

Now, we use the math.erf() method to directly calculate the error method for x=0 −

import math
x = 0
result = math.erf(x)
print("Error method for x =", x, ":", result)

Output

The result produced is as shown below −

Error method for x = 0 : 0.0