не рисуется в canvas ничего JS

function main() {
  let x, c, y;
  let step = document.forms.get.inputstep.value;
  let end = document.forms.get.inputend.value;
  let start = document.forms.get.inputstart.value;
  start = Number(start);
  end = Number(end);
  step = Number(step);
  c = Number(start);


  for (var item = start; item <= end; item = item + step) {
    start = item + start;
    x = item;
    y = (0.3 * Math.pow(Math.E, x + Math.pow(x, 0.5))); //0.3 e^ (x + x^0.5)
  }
  console.log("Цикл For->" + y);
  start = c;
  while (start < end) {
    x = start;
    y = (0.3 * Math.pow(Math.E, x + Math.pow(x, 0.5)));
    start = step + start;
  }
  alert("Цикл While->" + y)
  start = c;
  do {
    x = start;
    y = (0.3 * Math.pow(Math.E, x + Math.pow(x, 0.5)));
    start = step + start;
  }
  while (start <= end);
  console.log("Do while->" + y);
}

function draw() {
  var c = document.getElementById("Canvas");
  var ctx = c.getContext("2d");

  var start = document.getElementById("inputstart");
  var step = document.getElementById("inputstep");
  var end = document.getElementById("inputend");

  var y, x, c;
  ctx.strokeStyle = 'aqua';
  start = Number(start);
  end = Number(end);
  step = Number(step);
  ctx.lineWidth = 5;
  ctx.beginPath();
  ctx.moveTo(0, 0);

  for (var i = start; i <= end; i = i + step) {
    start = i + start;
    x = i;
    y = (0.3 * Math.pow(Math.E, x + Math.pow(x, 0.5)));
    ctx.lineTo(x, y);
  }
  ctx.stroke();
}
console.log(draw, main, );

<form id="get">
  Input Start<input name="inputstart" id="inputstart"> Input End<input name="inputend" id="inputend"> Input Step<input name="inputstep" id="inputstep">
</form>
<button onClick=draw()>Drawing</button>
<button onClick=main()>Forms</button><br/>
<canvas id="Canvas" width="500px" height="500px"></canvas>