simple linear system solver

function solve(a){
    if(!a[0][0])
        throw new Error("division by zero (can't solve)");
    if(a[0].length==2)
        return [a[0][1]/a[0][0]];
    a=a.sort(function(a,b)b[0]-a[0]);
    a[0]=a[0].map(function(e)e/a[0][0]);
    const b=solve(a.slice(1).map(function(e){const mul=e[0];return e.slice(1).map(function(e,i)e-mul*a[0][i+1])}));
    b.map(function(e,i)a[0][a[0].length-1]-=a[0][i+1]*e);
    b.unshift(a[0][a[0].length-1]);
    return b;
}