Write a function so that, when given a natural number N, the function returns the value max  n ∈ N : 12 + 22 + · · · + n 2 ≤ N

Write a function so that, when given a natural number N, the function returns the value max n ∈ N : 12 + 22 + · · · + n 2 ≤ N

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

[Walter Roberson]

The meaning of "n 2" is not clear in that question.

[TIanhang Hu]

n2 simply means n^2, how can it be not clear...

[Walter Roberson]

So the question is about finding the largest n such that the sum of squares of 1 to n is less than or equal to the original number? Hmmm, plausibly.

It would have been easy enough for the poster to have clarified that when asked a year ago.

Answer 1

[Andrei Bobrov]

your_function = @(n,m,N)sum((n+m):n:N);

use

>> n = 10;
m = 2;
N = 90;
>> your_function(n,m,N)
ans =
   376
>>

[Vin Sen Lee]

i m sorry. could you please explain the steps.

Answer 2

[Torsten]

n=floor((-7+sqrt(20*N+49))/10);

Best wishes

Torsten.

Answer 3

[Rusty]

function [ p ] = rusty( N)

a(1)=12;
i=1;
while sum(a(:))<=N
a(i+1)=a(i)+10;
i=i+1;

end
if sum(a(:))>N
a(end)=[];
end
if isempty(a)
    disp('N is less than 12');
    return
else
p=(a(end)-2)/10
end

[Vin Sen Lee]

i m sorry. could you please explain the steps.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/8026-best-way-s-to-master-matlab

[Rusty]

you just go and save this file. now open the command window and write : rusty(36), if N=36, and you will get the answer

Answer 4

[Márcio]

Write a function that for a given natural number nn returns the matrix which has 2 rows, in its first row every entry is 1, while in its second row there are the numbers n,n−1,…,1n,n−1,…,1 (in this order).

[Torsten]

N = 3624;
v = N:-1:1;
A = [ones(1,2*N);[v,v]]

A = 2×7248

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3624 3623 3622 3621 3620 3619 3618 3617 3616 3615 3614 3613 3612 3611 3610 3609 3608 3607 3606 3605 3604 3603 3602 3601 3600 3599 3598 3597 3596 3595