1.7 KiB
1.7 KiB
id | title | challengeType | forumTopicId | dashedName |
---|---|---|---|---|
5a23c84252665b21eecc7eb1 | Identity matrix | 5 | 302290 | identity-matrix |
--description--
An identity matrix is a square matrix of size \( n \times n \), where the diagonal elements are all 1
s (ones), and all the other elements are all 0
s (zeroes).
- \(\displaystyle I_{n}=\begin{bmatrix} 1 & 0 & 0 \cr 0 & 1 & 0 \cr 0 & 0 & 1 \cr \end{bmatrix}\)
--instructions--
Write a function that takes a number n
as a parameter and returns the identity matrix of order \( n \times n \).
--hints--
idMatrix
should be a function.
assert(typeof idMatrix == 'function');
idMatrix(1)
should return an array.
assert(Array.isArray(idMatrix(1)));
idMatrix(1)
should return [ [ 1 ] ]
.
assert.deepEqual(idMatrix(1), results[0]);
idMatrix(2)
should return [ [ 1, 0 ], [ 0, 1 ] ]
.
assert.deepEqual(idMatrix(2), results[1]);
idMatrix(3)
should return [ [ 1, 0, 0 ], [ 0, 1, 0 ], [ 0, 0, 1 ] ]
.
assert.deepEqual(idMatrix(3), results[2]);
idMatrix(4)
should return [ [ 1, 0, 0, 0 ], [ 0, 1, 0, 0 ], [ 0, 0, 1, 0 ], [ 0, 0, 0, 1 ] ]
.
assert.deepEqual(idMatrix(4), results[3]);
--seed--
--after-user-code--
let results=[[ [ 1 ] ],
[ [ 1, 0 ], [ 0, 1 ] ],
[ [ 1, 0, 0 ], [ 0, 1, 0 ], [ 0, 0, 1 ] ],
[ [ 1, 0, 0, 0 ], [ 0, 1, 0, 0 ], [ 0, 0, 1, 0 ], [ 0, 0, 0, 1 ] ]]
--seed-contents--
function idMatrix(n) {
}
--solutions--
function idMatrix(n) {
return Array.apply(null, new Array(n)).map(function (x, i, xs) {
return xs.map(function (_, k) {
return i === k ? 1 : 0;
})
});
}