// Wikipedia URL for General Matrix Multiplication Concepts: https://en.wikipedia.org/wiki/Matrix_multiplication
// This algorithm has multiple functions that ultimately check if the inputs are actually matrices and if two Matrices (that can be different sizes) can be multiplied together.
// matrices that are of the same size [2x2]x[2x2], and the second is the multiplication of two matrices that are not the same size [2x3]x[3x2].
// MatrixCheck tests to see if all of the rows of the matrix inputted have similar size columns
constmatrixCheck=(matrix)=>{
letcolumnNumb
for(letindex=0;index<matrix.length;index++){
if(index===0){
columnNumb=matrix[index].length
}elseif(matrix[index].length!==columnNumb){
// The columns in this array are not equal
}else{
returncolumnNumb
}
}
}
// tests to see if the matrices have a like side, i.e. the row length on the first matrix matches the column length on the second matrix, or vice versa.
// returns an empty array that has the same number of rows as the left matrix being multiplied.
// Uses Array.prototype.map() to loop over the first (or left) matrix and returns an empty array on each iteration.
constinitiateEmptyArray=(first,second)=>{
if(twoMatricesCheck(first,second)){
constemptyArray=first.map(()=>{
return['']
})
returnemptyArray
}else{
returnfalse
}
}
// Finally, `matrixMult` uses `Array.prototype.push()`, multiple layers of nested `for` loops, the addition assignment `+=` operator and multiplication operator `*` to perform the dot product between two matrices of differing sizes.
// Dot product, takes the row of the first matrix and multiplies it by the column of the second matrix, the `twoMatricesCheck` tested to see if they were the same size already.
// The dot product for each iteration is then saved to its respective index into `multMatrix`.