Static p5_sys::global::log

pub static log: LogInternalType

Calculates the natural logarithm (the base-e logarithm) of a number. This function expects the n parameter to be a value greater than 0.0. Maps to Math.log().

Examples

function draw() {
  background(200);
  let maxX = 2.8;
  let maxY = 1.5;

  // Compute the natural log of a value between 0 and maxX
  let xValue = map(mouseX, 0, width, 0, maxX);
  let yValue, y;
  if (xValue > 0) {
   // Cannot take the log of a negative number.
    yValue = log(xValue);
    y = map(yValue, -maxY, maxY, height, 0);

    // Display the calculation occurring.
    let legend = 'log(' + nf(xValue, 1, 2) + ')\n= ' + nf(yValue, 1, 3);
    stroke(150);
    line(mouseX, y, mouseX, height);
    fill(0);
    text(legend, 5, 15);
    noStroke();
    ellipse(mouseX, y, 7, 7);
  }

  // Draw the log(x) curve,
  // over the domain of x from 0 to maxX
  noFill();
  stroke(0);
  beginShape();
  for (let x = 0; x < width; x++) {
    xValue = map(x, 0, width, 0, maxX);
    yValue = log(xValue);
    y = map(yValue, -maxY, maxY, height, 0);
    vertex(x, y);
  }
  endShape();
  line(0, 0, 0, height);
  line(0, height / 2, width, height / 2);
}

Parameters

n number greater than 0