## pyspark.sql.functions.expm1

This function computes the result of e raised to the power of a given number, and then subtracts one. The mathematical representation is: expm1(x) = e^x – 1. While the formula may seem straightforward, you might wonder: why not just use a simple exponentiation? The answer lies in precision. For values of x close to zero, the result of e^x – 1 might not be accurate due to rounding errors. The expm1 function, however, ensures precision in these cases, making it invaluable for numerical computations. The **pyspark.sql.functions.expm1** function is more than just a mathematical computation. It exemplifies the intricacies and precision PySpark brings to the table for big data computations.

### Example with PySpark

Before we start, ensure you have PySpark and its dependencies set up. Now, let’s walk through an example using hardcoded data:

```
from pyspark.sql import SparkSession
from pyspark.sql.functions import expm1
# Initialize Spark session
spark = SparkSession.builder.appName("expm1_demo @ Freshers.in").getOrCreate()
# Create a DataFrame with hardcoded data
data = [("A", 0.1), ("B", 0.2), ("C", 0.01)]
df = spark.createDataFrame(data, ["ID", "Value"])
# Compute expm1 for each value
df_with_expm1 = df.withColumn("expm1_Value", expm1(df["Value"]))
# Show the results
df_with_expm1.show()
```

Output

```
+---+-----+--------------------+
| ID|Value| expm1_Value|
+---+-----+--------------------+
| A| 0.1| 0.10517091807564763|
| B| 0.2| 0.22140275816016985|
| C| 0.01|0.010050167084168058|
+---+-----+--------------------+
```

**Spark important urls to refer**