convolution product in js

conv.js

function conv(a, b, mode){
	var dl = b.length-1
	var aa=a.concat(repeat(0, dl)) //0-padding
	
	var c=[]
	for(var i=0;i<aa.length;i++){
		c[i]=0;
		for(var m=0;m<aa.length;m++)
			if (0<=i-m && i-m<b.length)
				c[i]+=aa[m]*b[i-m];

	}
	if (mode=='same'){
		var delta=Math.floor(b.length/2)
		return c.slice(delta, delta+a.length)
	}else if(mode=='valid'){
		return c.slice(b.length-1, c.length-b.length+1)
	}else
		return c;
}	
	
function conv2(a, b, mode){
	var dl = b.length-1
	var aa=[] //0-padding
	aa=aa.concat( a.map(function(r){return r.concat(repeat(0, dl))}) )
	for(var i=0;i<dl; i++)
		aa.push(repeat(0, a.length+2*dl));
	var c=[]
	for(var i=0;i<aa.length;i++){
		c[i]=[]
		for(var j=0;j<aa[0].length;j++){
			c[i][j]=0;
			for(var m=0;m<aa.length;m++)
				for(var n=0;n<aa[0].length;n++)
					if (0<=i-m && i-m<b.length && 0<=j-n && j-n<b[0].length)
						c[i][j]+=aa[m][n]*b[i-m][j-n];
		}
	}
	if (mode=='same'){
		var delta=Math.floor(b.length/2)
		return c.slice(delta, delta+a.length).map(function(r){return r.slice(delta, delta+a.length)})
	}else if(mode=='valid'){
		return c.slice(b.length-1, c.length-b.length+1).map(function(r){return r.slice(b.length-1, c.length-b.length+1)})
	}else
		return c;
}

function repeat(x, n){
    return Array.apply(null, {length:n}).map(function(){return x})
}