Problem 972. Set a diagonal
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
Solution Stats
Problem Comments
-
10 Comments
Added new test case 9 Oct. 2012
Are you missing some text from your example?
Test suggestion: Stick a zero in one of your v vectors and you'll eliminate some of the shorter answers.
Yes. All solutions with find don't work with 0 in v.
Thanks for the suggestions -- I updated the text, added a new test case and rescored.
@Nicholas Howe: The test suggestion meant: stick a 0 in v, and this 0 is meant to replace an entry of M that was unequal to 0. In other words: the new test-case doesn't make a difference (and hence is useless) if M is a null-matrix.
The cases with d=0 are working for me but your test cases are giving error..... What's this?
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
Please add a precision threshold for floating numbers. Sometimes I get results with an error ~ e-17 close, but still not accepted.
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 commentsProblem Recent Solvers286
Suggested Problems
-
Maximum running product for a string of numbers
2173 Solvers
-
1553 Solvers
-
Split a string into chunks of specified length
1777 Solvers
-
Decimation - Optimized for speed
172 Solvers
-
Mersenne Primes vs. All Primes
620 Solvers
More from this Author11
Problem Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!