## Turn this summation into Python code (int or float)

I need to turn the following summation into Python code: This Summation

the summation length N is known.

I'm struggling with the second summation I need something like this

for i in range(N): (1 - (for j in range(N): sum(x[i][j]))**2

But the second for loop is obviously not going to work (Syntax Error) How can I iterate over j within the first for loop? The result needs to be saved in a variable

Thank you very much

sum = 0 for i in range(N): sum_inside = 0 for j in range(N): sum_inside += x[i][j] sum += (1 - sum_inside)**2

**Python Program to Add Two Numbers,** In this program, you will learn to add two numbers and display it using print() function. The program below calculates the sum of two numbers entered by the user. returns a string, we convert the string into number using the float() function. Float method is part of python standard library which converts a number or a string containing numbers to a float data type. There are following rules when a string is considered to be valid for converting it to a float.

`sum`

can take a generator expression, so you can make this a pretty clean one-liner with:

total = sum((1 - sum(x[i][j] for j in range(N)))**2 for i in range(N))

If `N`

is such that you are actually summing all the elements (array is square and N == number of rows/columns) in the array you can do away with the ranges and just use:

sum((1 - sum(n for n in row))**2 for row in x)

which you can also do in numpy with something like:

x = np.array(x) np.sum((1 - np.sum(x, axis=1))**2)

or if `N`

is to take a slice of the matrix:

a = np.array(x) N = 2 np.sum((1 - np.sum(a[0:N, 0:N], axis=1))**2)

**How to sum a list of numbers in python ?,** To add all the elements of a list, a solution is to use the built-in function sum(), l = ['a',1,'f',3.2,4] >>> sum([i for i in l if isinstance(i, int) or isinstance(i, float)]) 8.2� Let us dive into the numeric data type float. And later into the setting of precision for the subsequent float values. FLOAT: This data type holds the real number values. Example Of Float Number: >>>num=3.898 >>>print(type(num)) Output: <class'float'> Float Precision in Python is performed in numerous ways using different methods as below:

I hope you aren't asking stack overflow to do your homework!

The summation is a simple nested comprehension:

sum(1 - sum(x[i,j] for j in range(1, N+1)) ** 2 for i in range(1, N+1))

Don't take my word for it though; it's a good idea to check the results. Here I am using x as a tuple-keyed dict.

Be aware that the image ranges from 1 to N, not from 0 to N-1. If x is a 2d array, then that would be okay if you are adjusting for zero-indexing.

@MarkMeyer has a more comprehensive answer than this one. Regarding vectors / multi-dimensional arrays, we have recently decided it's a little more pythonic to represent them as tuple-keyed dicts instead of nested lists. For instance, with x above, we define it as follows:

x = {(i,j): fn(i,j) for j in range(1, N) for i in range(1, N)}

The major advantage is that there is no preference of index, and we are able to use filter/map for most functions.

**4.8. Sum of Numbers - Python,** Starting out with Python, Third Edition, Tony Gaddis Ch.. Sign in to make your opinion count Duration: 18:56
Posted: Nov 22, 2016 We can convert an int to float using the float() function. Similarly, we can use int() function to convert a float to int. We can use complex() function to convert an int or float to the complex number, the imaginary part will be 0j. We can’t convert a complex number to int or float.

I think this is may be a solution for your problem. Still x[i][j] is confusing.

N=int(input("Enter the value of N ")) Sum=0 for i in range(N): for j in range(N): Sum =Sum+( 1 - (sum(x[i][j]))**2) print(Sum)

**5.3. Calculating the Sum of a List of Numbers — Problem Solving ,** How can we take this idea and turn it into a Python program? First, let's restate the sum problem in terms of Python lists. We might say the the sum of the list� Floats with very big or very small absolute value can be written using a scientific notation. Eg., the distance from the Earth to the Sun is 1.496·10 11, or 1.496e11 in Python. The mass of one molecule of the water is 2.99·10-23, or 2.99e-23 in Python. One can cast float objects to int objects by discarding the fraction part using the int

**float() in Python,** Python | Filter out integers from float numpy array � Python program to convert float decimal to Octal number � Chinmoy Lenka. Check out this� If you want to convert float to integer variable type in Python. You have to use the int () function of Python. Pass the float variable as the argument of the int () function in Python. To print the resulted integer value after conversion, you have to u se the Python print function.

It is a type of type conversion in which handles automatically convert one data type to another without any user involvement. In the above example, it can be seen that Python handles all the type conversion automatically without any user involvement. A string is generally a sequence of one or more

23423.000000000000000001 is not a standard python float. float("23423.000000000000000001") = 23423 (the questions wanted float or int - the required accuracy was not stated - other then float). – pev.hall Mar 8 '14 at 5:11

##### Comments

- I don't understand what you want to achieve with the
`1 - for ...`

which obviously not works as you point out yourself. Do you want to subtract the result from 1? - I would expect
`x`

to be vector of some sort not a function with this notation. - @MarkMeyer, yes it's true. But even with vectors, there's a difference between 0..n and 1..n+1, no? Likewise, a vector can always be interchanged with a function.. It's a preference thing, I guess..
- Sure, that's fair enough @Konchog.
- @MarkMeyer, I decided you were right in this example - but changed it to a tuple-keyed dict (our current preference for this sort of structure).