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---
title: Element-wise operations
id: 599c333915e0ea32d04d4bec
challengeType: 5
---
## Description
< section id = 'description' >
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Implement basic element-wise matrix-matrix and scalar-matrix operations.
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< strong > Implement:< / strong >
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< ul >
< li > addition< / li >
< li > subtraction< / li >
< li > multiplication< / li >
< li > division< / li >
< li > exponentiation< / li >
< / ul >
The first parameter will be the operation to be performed, for example, "m_add" for matrix addition and "s_add" for scalar addition. The second and third parameters will be the matrices on which the operations are to be performed.
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< / section >
## Instructions
< section id = 'instructions' >
< / section >
## Tests
< section id = 'tests' >
```yml
tests:
- text: < code > operation</ code > is a function.
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testString: assert(typeof operation === 'function', '< code > operation< / code > is a function.');
- text: < code > operation("m_add",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[2,4],[6,8]]</ code > .
testString: assert.deepEqual(operation('m_add', [[1, 2], [3, 4]], [[1, 2], [3, 4]]), [[2, 4], [6, 8]], '< code > operation("m_add",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[2,4],[6,8]]< / code > .');
- text: < code > operation("s_add",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[3,4],[5,6]]</ code > .
testString: assert.deepEqual(operation('s_add', [[1, 2], [3, 4]], 2), [[3, 4], [5, 6]], '< code > operation("s_add",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[3,4],[5,6]]< / code > .');
- text: < code > operation("m_sub",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[0,0],[0,0]]</ code > .
testString: assert.deepEqual(operation('m_sub', [[1, 2], [3, 4]], [[1, 2], [3, 4]]), [[0, 0], [0, 0]], '< code > operation("m_sub",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[0,0],[0,0]]< / code > .');
- text: < code > operation("m_mult",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[1,4],[9,16]]</ code > .
testString: assert.deepEqual(operation('m_mult', [[1, 2], [3, 4]], [[1, 2], [3, 4]]), [[1, 4], [9, 16]], '< code > operation("m_mult",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[1,4],[9,16]]< / code > .');
- text: < code > operation("m_div",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[1,1],[1,1]]</ code > .
testString: assert.deepEqual(operation('m_div', [[1, 2], [3, 4]], [[1, 2], [3, 4]]), [[1, 1], [1, 1]], '< code > operation("m_div",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[1,1],[1,1]]< / code > .');
- text: < code > operation("m_exp",[[1,2],[3,4]],[[1,2],[3,4]])</ code > should return < code > [[1,4],[27,256]]</ code > .
testString: assert.deepEqual(operation('m_exp', [[1, 2], [3, 4]], [[1, 2], [3, 4]]), [[1, 4], [27, 256]], '< code > operation("m_exp",[[1,2],[3,4]],[[1,2],[3,4]])< / code > should return < code > [[1,4],[27,256]]< / code > .');
- text: < code > operation("m_add",[[1,2,3,4],[5,6,7,8]],[[9,10,11,12],[13,14,15,16]])</ code > should return < code > [[10,12,14,16],[18,20,22,24]]</ code > .
testString: assert.deepEqual(operation('m_add', [[1, 2, 3, 4], [5, 6, 7, 8]], [[9, 10, 11, 12], [13, 14, 15, 16]]), [[10, 12, 14, 16], [18, 20, 22, 24]], '< code > operation("m_add",[[1,2,3,4],[5,6,7,8]],[[9,10,11,12],[13,14,15,16]])< / code > should return < code > [[10,12,14,16],[18,20,22,24]]< / code > .');
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'js-seed' >
```js
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function operation(op, arr1, arr2) {
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// Good luck!
}
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
function operation(op, arr1, arr2) {
const ops = {
add: ((a, b) => a + b),
sub: ((a, b) => a - b),
mult: ((a, b) => a * b),
div: ((a, b) => a / b),
exp: ((a, b) => Math.pow(a, b))
};
const ifm = op.startsWith('m');
const doOp = ops[op.substring(2)];
for (let i = 0; i < arr1.length ; i + + ) {
for (let j = 0; j < arr1 [ 0 ] . length ; j + + ) {
arr1[i][j] = doOp(arr1[i][j], (ifm) ? (arr2[i][j]) : (arr2));
}
}
return arr1;
}
```
< / section >