# Python | ldexp() function

`ldexp()` function is one of the Standard math library function in Python, which returns x * (2**i). This is also called as inverse of Python `frexp()` function.

Syntax: math.ldexp(x, i)

Parameters:
x : Any valid number (+ve or -ve)
i : Any valid number (+ve or -ve)

Returns : Returns the value of x * (2**i).

For example, if x = 3 and i = 4 then, Math.ldexp(3, 4) = 3*16 = 48.

Code #1:

 `# Python3 code demonstrate ldexp() function ` ` `  `# importing math library ` `import` `math  ` ` `  `# ldexp() Function on +ve nd -ve Numbers ` `print``(math.ldexp(``9``, ``3``)) ` `print``(math.ldexp(``-``5``, ``2``)) ` ` `  `# ldexp() Function on fractional Number ` `print``(math.ldexp(``3.5``, ``2``)) ` `print``(``'%.2f'` `%``math.ldexp(``-``6.8``, ``3``)) `

Output:

```72.0
-20.0
14.0
-54.40
```

Code #2:

 `# Python3 code demonstrate ldexp() function ` ` `  `# importing math library ` `import` `math  ` ` `  `# Tuple Declaration  ` `tpl ``=` `(``9``, ``-``5``, ``3.5``, ``-``6.8``) ` ` `  `# List Declaration  ` `lst ``=` `[``13``, ``4``, ``8.4``, ``-``6.7``] ` ` `  `# ldexp() Function on +ve nd -ve Numbers ` `print``(math.ldexp(tpl[``0``], ``3``)) ` `print``(math.ldexp(tpl[``3``], ``2``)) ` ` `  `# ldexp() Function on fractional Number ` `print``(math.ldexp(lst[``1``], ``2``)) ` `print``(``'%.2f'` `%``math.ldexp(lst[``2``], ``3``)) `

Output:

```72.0
-27.2
16.0
67.20```

Code #3: If the X value or i value argument is not a number, ldexp() function will return TypeError.

 `# Python3 code demonstrates when error occurs ` ` `  `# importing the math library ` `import` `math ` ` `  `# string value taken  ` `print``(math.ldexp(``'25'``, ``5``)) ` `print``(math.ldexp(``25``, ``'5'``)) `

Output:

```TypeError: a float is required
TypeError: a float is required```

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