dist/d3-sankey-circular.es.js
function scaleSankeySize(graph, margin) {

    var maxColumn = max(graph.nodes, function (node) {
      return node.column;
    });

    var currentWidth = x1 - x0;
    var currentHeight = y1 - y0;

    var newWidth = currentWidth + margin.right + margin.left;
    var newHeight = currentHeight + margin.top + margin.bottom;

    var scaleX = currentWidth / newWidth;
    var scaleY = currentHeight / newHeight;

    x0 = x0 * scaleX + margin.left;
    x1 = margin.right == 0 ? x1 : x1 * scaleX;
    y0 = y0 * scaleY + margin.top;
    y1 = y1 * scaleY;

    graph.nodes.forEach(function (node) {
      node.x0 = x0 + node.column * ((x1 - x0 - dx) / maxColumn);
      node.x1 = node.x0 + dx;
    });

    return scaleY;
  }
function scaleSankeySize(graph, margin) {

    var maxColumn = max(graph.nodes, function (node) {
      return node.column;
    });

    var currentWidth = x1 - x0;
    var currentHeight = y1 - y0;

    var newWidth = currentWidth + margin.right + margin.left;
    var newHeight = currentHeight + margin.top + margin.bottom;

    var scaleX = currentWidth / newWidth;
    var scaleY = currentHeight / newHeight;

    x0 = x0 * scaleX + margin.left;
    x1 = margin.right == 0 ? x1 : x1 * scaleX;
    y0 = y0 * scaleY + margin.top;
    y1 = y1 * scaleY;

    graph.nodes.forEach(function (node) {
      node.x0 = x0 + node.column * ((x1 - x0 - dx) / maxColumn);
      node.x1 = node.x0 + dx;
    });

    return scaleY;
  }
Update the x0, y0, x1 and y1 for the sankeyCircular, to allow space for any circular links