{"id":4676,"date":"2020-03-31T18:19:57","date_gmt":"2020-03-31T18:19:57","guid":{"rendered":"https:\/\/www.askpython.com\/?p=4676"},"modified":"2022-08-06T13:13:14","modified_gmt":"2022-08-06T13:13:14","slug":"python-complex-method","status":"publish","type":"post","link":"https:\/\/www.askpython.com\/python\/built-in-methods\/python-complex-method","title":{"rendered":"How to Use the Python complex() method"},"content":{"rendered":"\n

The Python complex()<\/strong> method is used to create a complex number from other primitive data-types. This is useful whenever you want to perform complex arithmetic and transformations quickly.<\/p>\n\n\n\n

Let’s take a look at how we can use this method.<\/p>\n\n\n\n

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Syntax of Python complex()<\/h2>\n\n\n\n

This function returns a complex number, which contains a real part, and an imaginary part. The complex number is of the class complex<\/code> datatype.<\/p>\n\n\n\n

Therefore, the function call syntax is:<\/p>\n\n\n

\nclass complex([real[, imag]])\n<\/pre><\/div>\n\n\n
The complex number will be of the form:<\/p>\n\n\n
\ncomplex_number = real + imag*j\n<\/pre><\/div>\n\n\n
Here, j<\/code> is the imaginary number (sqrt(-1))<\/p>\n\n\n\n
The Python complex()<\/code> method will return this complex number.<\/p>\n\n\n\n
Let’s look at some examples, to get familiar with this method.<\/p>\n\n\n\n
You may think that we could use only integers and floats to construct the complex number, but that’s not that case!<\/p>\n\n\n\n
We can also construct it from a string, hexadecimal, binary too, or even from another complex number!<\/p>\n\n\n\n
We’ll take a look at some examples, to illustrate this point.<\/p>\n\n\n\n
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Using the Python complex() method<\/h2>\n\n\n\n
Calling complex() without any parameter<\/h3>\n\n\n\n
We can call this method without passing any arguments to it. This will return the zero complex number 0j<\/code>.<\/p>\n\n\n
\na = complex()\nprint(type(a))\nprint(a)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n<class 'complex'>\n0j\n<\/pre><\/div>\n\n\n
Calling Python complex() using numeric parameters<\/h3>\n\n\n\n
This will construct the desired complex number of the form a + bj<\/code>, where a<\/code> and b<\/code> are the numeric parameters.<\/p>\n\n\n
\na = complex(1, 2)\nprint(a)\n\nb = complex(1, 1.5)\nprint(b)\n\nc = complex(-1.5, 3.414)\nprint(c)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n(1+2j)\n(1+1.5j)\n(-1.5+3.414j)\n<\/pre><\/div>\n\n\n
Calling complex() with Hexadecimal \/ Binary arguments<\/h3>\n\n\n\n
We can also directly pass hexadecimal or binary number into this, without converting it to an integer.<\/p>\n\n\n
\na = complex(0xFF)  # hexadecimal\nprint(a)\n\nb = complex(0b1010, -1)  # binary\nprint(b)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n(255+0j)\n(10-1j)\n<\/pre><\/div>\n\n\n
Calling complex() using another complex number<\/h3>\n\n\n\n
We can also pass another complex number, when constructing a complex number using complex()<\/code><\/p>\n\n\n
\na = 1 + 2j\nb = complex(a, -4) # Construct using another complex number\nprint(b)\nc = complex(1+2j, 1+2J)\nprint(c)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n(1-2j)\n(-1+3j)\n<\/pre><\/div>\n\n\n
Since both the arguments are added according to the form a + b*j<\/code>, in the first case, the result will be: 1 + 2j + (-4*j) = 1 – 2j<\/strong><\/p>\n\n\n\n
In the second case, we have (since j*j = -1): 1+2j + (1+2j)*j = (1 + 2j + j – 2) = -1+3j<\/strong><\/p>\n\n\n\n
Calling Python complex() using string arguments<\/h3>\n\n\n\n
We can also pass string with it, provided that it does not<\/strong> have any white space in between. The string must only be of the form “a+bj”, i.e, a string which can represent a complex number.<\/p>\n\n\n\n
If we are using a string, we can only use one argument<\/strong>.<\/p>\n\n\n
\na = complex("1+2j")\nprint(a)\n<\/pre><\/div>\n\n\n
Output<\/strong><\/p>\n\n\n
\n(1+2j)\n<\/pre><\/div>\n\n\n
If the string has whitespaces or any other extraneous character, a ValueError<\/code> exception will be raised.<\/p>\n\n\n
\nb = complex("2 + 4j")\nprint(b)\n<\/pre><\/div>\n\n\n
This will raise a ValueError<\/code>, since there are spaces in the string.<\/p>\n\n\n\n
Similarly, if we pass two arguments to Python complex()<\/code>, it will raise a TypeError<\/code> exception, as we are not allowed to pass multiple arguments if the first argument is a String.<\/p>\n\n\n\n
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Conclusion<\/h2>\n\n\n\n
In this article, we learned how we can construct a complex number from different data-types, using the built-in complex()<\/code> method. If you want to learn about other Python built-in functions visit here<\/a>.<\/p>\n\n\n\n
References<\/h2>\n\n\n\n