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Unless you’re a math genius, you haven’t memorized all of the square roots. And even if you have, someone else looking at your code may not know you are. This means that they may need to verify that you wrote the correct square roots - just redo the work.
If you’ve used Python’s square root function, it’s clear that a root is squared. Someone else who examines your code will know that it is correct. As a bonus, no one needs to open the calculator!
What is Python sqrt () ?
Whether you are using the Pythagorean Theorem or working on a quadratic equation, Python’s square root function - sqrt () - can help you solve your problems. As you might have guessed,
sqrt () will return the square of the number you pass as a parameter.
sqrt () method can be useful because it is fast and accurate. This short tutorial covers what you can pass as a parameter to
sqrt (), ways to work around invalid parameters, and an example to help you understand. You can get the square root of a number by raising it to a power of 0.5 using Python’s exponent operator (**) or the
pow () function.
When you are working with multiple numbers that require square roots, you will find that using the
sqrt () function is more elegant than using multiple operators with exponent with " 0.5 ". Also, it is clearer. It can be easy to forget or lose the extra asterisk ("*"), which will completely change the instruction to a multiplication instruction, giving you a completely different result.
Syntax of the Python square root function
The general syntax used to call the
sqrt () function is:
In the above code snippet, "x" is the number whose square root you want to calculate. The number that you pass as a parameter to the square root function can be greater than or equal to 0. Note that you can only pass one number.
But what does the " math " part refer to in the above syntax ? The math module is a Python library that contains many useful math functions, including the
sqrt () function. To use
sqrt (), you will need to import the math module, as this is where the code to run the function is stored. By prefixing "math" to
sqrt (), the compiler knows that you are using a function,
sqrt (), belonging to the "math" library class .
The way to import the math module is to write the keyword "import" with the module name - "math" in this case. Your import instruction is a single line that you write before the code containing a
sqrt () function:
The result of the square root function is a floating point number (float). For example, the result of using
sqrt () on 81 would be 9.0, which is a floating point number.
Include the math import statement at the top of any file or terminal / console session that contains code using
How to use Python’s sqrt () method
You can pass positive numbers of type float or int (integer). We saw an int, 81, as a parameter in the previous example. But we can also float, 70.5, for example:
The result of this calculation is 8.916277250063503. As you can see, the result is quite precise. You can now see why it makes sense for the output to always be a double, even if the square root of a number is as simple as "9".
You can also pass a variable that represents a number:
And you can also save the result in a variable:
Save it in a variable will facilitate printing to the screen:
Working with negative numbers with abs ()
The square root of a number cannot be negative. This is because a square is the product of the number by itself, and if you multiply two negative numbers, the negatives cancel out and the result will always be positive. If you try to pass a negative number to
sqrt (), you will receive an error message and your calculation will fail.
abs () function returns the absolute value of a given number. The absolute value of -9 would be 9. Likewise, the absolute value of 9 is 9. Since
sqrt () is designed to work with positive numbers, a negative number would return a ValueError.
Suppose you pass the variables to
sqrt () and you can’t tell if they are all positive without checking the long lines of code to find the values variables. At the same time, you don’t even want a ValueError to be raised. Even if you are watching, another programmer may come in and unintentionally add a negative variable, so your code will throw an error. To avoid this madness, you can use
abs () function will take your value and translate it to an absolute value (81 in this case). Then the non-negative absolute value will be passed to the
sqrt () function, which is what we want, so that we don’t have any annoying errors!
List comprehension and sqrt ()
What if you had more numbers than would you like to get the square roots? You can calculate the square root for all in one using an inline for loop called list comprehension .
First create a list with the values ‚Äã‚Äãyou want to get square roots.
Second, we iterate through the list with a for loop expression to get the square root of each value. The syntax of an inline for loop expression is for number to numbers, where "number" is each member of the list we named "numbers". We ’ll save the results in a list we’ll call "squaredNumbers".
print () statement to see the results of squaring the list of numbers.
for-Statements and sqrt ()
You can also use a typical for loop. Although using a typical for loop means that you have to write more lines of code than in the previous example, for loops may be easier to read for some people.
First, declare the list in which you want to save the calculated values.
We will use the same list of values ‚Äã‚Äã("numbers") than in the previous example and iterate through each of its elements, which we called "number".
Now if you print this new list of squared numbers, you get the same result as the previous example.
Example with diagonal distances ()
There are many uses for
sqrt (). An example is that you can use it to find the diagonal distance between two points that intersect at right angles, such as street corners or points on a lot or a design drawing.
This is because the diagonal distance between two points intersecting at right angles would be equivalent to the hypotenuse of a triangle, and for that you could use the Pythagorean theorem, (a 2 sup> + b 2 ) = c 2 , which uses square roots. This formula is very useful because in city streets, house projects and fields it can be easy to get the length and width measurements but not for the diagonals between them.
You must use
sqrt () on the hypotenuse, c 2 , to get the length. Another way to rewrite the Pythagorean Theorem is c = a 2 + b 2 . in the form of a triangle.
We ran lengthwise and crosswise, so we cut our or starting point. To get precision and count how many feet you’ve run, you can calculate the feet of the diagonal you’ve cut using length and width (whose length in feet you can save as variables "a" and " b ") from the park:
The result would be 47.43416490252569. So when you add this to the other two lengths, you know it and that’s it. The total number of feet you ran on your right triangle course in the park.
What else can you do with Sqrt () ?
Now that you know the basics, the possibilities are endless. For example:
- Use it in a formula to determine prime numbers.
- Perform any number of operations that require a precise square root.
- Use it to calculate distances.
In this article, you learned how to use
sqrt () with positive and negative numbers, lists, and how to rework the Pythagorean theorem so that four math calculations are done with
Do you have to work with whole numbers instead of floating point numbers ?
math.isqrt () returns the square as an integer and rounds it down to the nearest whole number. You can also use
sqrt () with libraries other than the "math" library such as numPy , a Python library used for working with arrays.
How to get an absolute file path in Python
Given a path such as
"mydir/myfile.txt", how do I find the file"s absolute path relative to the current working directory in Python? E.g. on Windows, I might end up with:
>>> import os
Also works if it is already an absolute path:
>>> import os
How to check if a path is absolute path or relative path in a cross-platform way with Python?
UNIX absolute path starts with "/", whereas Windows starts with alphabet "C:" or "".
Does python have a standard function to check if a path is absolute or relative?
True if the path is absolute,
False if not. The documentation says it works in windows (I can confirm it works in Linux personally).
How to join absolute and relative urls?
I have two urls:
url1 = "http://127.0.0.1/test1/test2/test3/test5.xml"
url2 = "../../test4/test6.xml"
How can I get an absolute url for url2?
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