Problem 972. Set a diagonal

Created by Nicholas Howe
Appears in CUP Challenge

Difficulty:Rate

Solve Later
Add To GroupÃ‚

Given a matrix M, row vector v of appropriate length, and diagonal index d (where 0 indicates the main diagonal and off-diagonals are identified by positive and negative integers), return a new matrix where the specified diagonal of M is replaced by v. You may assume that v is the correct length for the specified diagonal. If d is not provided, assume it is zero.
For example,
M = magic(5);
setDiagonal(M,1:4,-1)
ans =
  17    24     1     8    15
   1     5     7    14    16
   4     2    13    20    22
  10    12     3    21     3
  11    18    25     4     9

Solve

Solution Stats

1389 Solutions
299 Solvers

Last Solution submitted on Mar 11, 2025

Last 200 Solutions

Problem Comments

10 Comments

10 Comments

Show 7 older comments

Riccardo Dessì on 25 Jun 2018

please, when you make use of test cases with floating point numbers specify a common precision, otherwise is impossible to pass the suite and people need to be noob! thx in advanced

Akrem Hadji on 17 Oct 2020

Please add a precision threshold for floating numbers. Sometimes I get results with an error ~ e-17 close, but still not accepted.

Anton Casas on 2 Nov 2020

Test cases with 2 input arguments can be very tricky for people without knowledge of nargin, and that is off-topic here. I think a hint should be added on the problem description.

Solution Comments

Show comments

Group

CUP Challenge

11 Problems
4037 Finishers

Problem Recent Solvers299

Problem Tags

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!