JSFiddle - React, Tailwind, and code Playground

HTML

<div id="output"></div>

JavaScript

var _f = [
[0,0,0,0,0],
[0,0,0,0,0],
[0,0,1,1,0],
[0,0,1,2,0],
[0,0,0,0,0]
];

var _h = [
[1,1],
[1,2]
];

var xres = _f[0].length;
var yres = _f.length;

function f(x,y) {
	return (_f[x-1] || 0)[y-1] || 0;
}
function h(x,y) {
	return (_h[x-1] || 0)[y-1] || 0;
}



function C_minus(x,y) {
	var acc = 0;
	for (var p = 1; p <= xres; p++) {
		for (var q = 1; q <= yres; q++) {
			acc += f(p,q) * h(p-x, q-y);
		}
	}
	return acc;
}


function C_plus(x,y) {
	var acc = 0;
	for (var p = 1; p <= xres; p++) {
		for (var q = 1; q <= yres; q++) {
			acc += f(p,q) * h(p+x, q+y);
		}
	}
	return acc;
}

function log(str) {
	document.getElementById("output").innerHTML += (str || "") + "</br>";
}

function printMat(f) {
	for (var q = 0; q < xres; q++) {
		var str = "";
		for (var p = 0; p < xres; p++) {
			str += f(p,q) + ", ";
		}
		log(str);
	}
}
log("C with minus:");
printMat(C_minus);
log();
log("C with plus:");
printMat(C_plus);