Matrix multiplication: Difference between revisions
→{{header|JavaScript}}
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=={{header|JavaScript}}==
===Iterative===
{{works with|SpiderMonkey}} for the <code>print()</code> function
Line 2,010 ⟶ 2,012:
<pre>-7,-6,11
-17,-20,25</pre>
===Functional (ES5)===
{{trans|Haskell}}
<lang JavaScript>(function () {
'use strict';
// matrixMultiply:: [[n]] -> [[n]] -> [[n]]
function matrixMultiply(a, b) {
var bt = transpose(b);
return concatMap(a, function (aRow) {
return [concatMap(bt, function (bCol) {
return [sum(zipWith(prod, aRow, bCol))];
})]
});
}
return matrixMultiply(
[[1, 2],
[3, 4]],
[[-3, -8, 3],
[-2, 1, 4]]
);
// --> [[-7, -6, 11], [-17, -20, 25]]
// GENERIC LIBRARY FUNCTIONS
// concatMap :: [a] -> (a -> [b]) -> [b]
function concatMap(xs, f) {
return [].concat.apply([], xs.map(f));
}
// (a -> b -> c) -> [a] -> [b] -> [c]
function zipWith(f, xs, ys) {
return xs.length === ys.length ? (
xs.map(function (x, i) {
return f(x, ys[i]);
})
) : undefined;
}
// [[a]] -> [[a]]
function transpose(lst) {
return lst[0].map(function (_, iCol) {
return lst.map(function (row) {
return row[iCol];
});
});
}
// sum :: (Num a) => [a] -> a
function sum(xs) {
return xs.reduce(function (a, x) {
return a + x;
}, 0);
}
// product :: n -> n -> n
function prod(a, b) {
return a * b;
}
})();</lang>
{{Out}}
<pre>[[-7, -6, 11], [-17, -20, 25]]</pre>
=={{header|jq}}==
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