Linear Functions

A Function is special relationship where each input has an output

Linear Functions

A Function is special relationship where each input has an output.

A function is often written as f(x) where x is the input:

// Generate values var xValues = []; var yValues = []; for (var x = 0; x <= 10; x += 1) { xValues.push(x); yValues.push(x); } // Display using Plotly var data = [{x:xValues, y:yValues, type:"lines"}]; var layout = {title: "f(x) = x"}; Plotly.newPlot("myPlot1", data, layout);

Results from f(x) = x

xyy = x
11y = x = 1
22y = x = 2
33y = x = 3
44y = x = 4
55y = x = 5

// Generate values var xValues = []; var yValues = []; for (var x = 0; x <= 10; x += 1) { xValues.push(x); yValues.push(x*2); } // Display using Plotly var data = [{x:xValues, y:yValues, type:"lines"}]; var layout = {title: "f(x) = 2x"}; Plotly.newPlot("myPlot2", data, layout);

Results from f(x) = 2x

xyy = 2x
12y = 2x = 2
24y = 2x = 4
36y = 2x = 6
48y = 2x = 8
510y = 2x = 10

Linear Equations

A Linear Equation is an equation for a straight line:

  • y = x
  • y = x*2
  • y = x*2 + 7
  • y = ax + b
  • 5x = 3y
  • y/2 = 6
  • var exp1 = "x"; var exp2 = "x*2"; var exp3 = "x*2 + 7"; // Generate values var x1Values = []; var x2Values = []; var x3Values = []; var y1Values = []; var y2Values = []; var y3Values = []; for (var x = 0; x <= 10; x += 1) { x1Values.push(x); x2Values.push(x); x3Values.push(x); y1Values.push(eval(exp3)); y2Values.push(eval(exp2)); y3Values.push(eval(exp1)); } // Define Data var data = [ {x: x1Values, y: y1Values, mode:"lines"}, {x: x2Values, y: y2Values, mode:"lines"}, {x: x3Values, y: y3Values, mode:"lines"} ]; var layout = {title: "[y=" + exp3 + "] [y=" + exp2 + "] [y=" + exp1 + "]"}; // Display using Plotly Plotly.newPlot("myPlot4", data, layout);

    Non-Linear Equations

    A Linear Equation can NOT contain exponents or square roots:

  • y = x**2
  • y = Math.sqrt(x)
  • y = Math.sin(x)
  • Linear Regression

    A Linear regression tries to model the relationship between two variables by fitting a linear graph to data.

    One variable (x) is considered to be data, and the other (y) is considered to be dependent.

    For example, a Linear Regression can be a model to relate the price of houses to their size.

    Linear Least Squares

    Linear algebra is used to solve Linear Equations.

    Linear Least Squares (LLS) is a set of formulations for solving statistical problems involved in Linear Regression.