Piecewise Graphing Calculator

Piecewise Function Graphing Calculator

Use this calculator to generate a table of (x, y) coordinates for a piecewise-defined function over a specified range. You can define up to three pieces for your function.

Define Your Piecewise Function

Enter the mathematical expressions for each piece and their corresponding boundaries. Use 'x' as the variable. For multiplication, use '*'. For powers, use 'Math.pow(base, exponent)'. For example, x squared is 'Math.pow(x, 2)'.

Supported Math functions: Math.sin(), Math.cos(), Math.tan(), Math.sqrt(), Math.abs(), Math.log() (natural log), Math.log10(), Math.PI, Math.E.






Graphing Range and Step Size




Generated (x, y) Coordinates

Enter your function details and click "Generate Points" to see the coordinates.

function evaluateExpression(expression, x_val) { try { // Replace common math functions and constants for evaluation var sanitizedExpression = expression .replace(/sin\(/g, 'Math.sin(') .replace(/cos\(/g, 'Math.cos(') .replace(/tan\(/g, 'Math.tan(') .replace(/sqrt\(/g, 'Math.sqrt(') .replace(/pow\(/g, 'Math.pow(') .replace(/log\(/g, 'Math.log(') // Natural log .replace(/log10\(/g, 'Math.log10(') .replace(/abs\(/g, 'Math.abs(') .replace(/PI/g, 'Math.PI') .replace(/E/g, 'Math.E'); // Use new Function for safer evaluation than direct eval() // This creates a function that takes 'x' as an argument var func = new Function('x', 'return ' + sanitizedExpression + ';'); return func(x_val); } catch (e) { console.error("Error evaluating expression:", expression, "at x =", x_val, e); return NaN; // Indicate an error in expression } } function calculatePiecewiseGraph() { var functionExpr1 = document.getElementById("functionExpr1").value; var functionExpr2 = document.getElementById("functionExpr2").value; var functionExpr3 = document.getElementById("functionExpr3").value; var boundary1 = parseFloat(document.getElementById("boundary1").value); var boundary2 = parseFloat(document.getElementById("boundary2").value); var graphStartX = parseFloat(document.getElementById("graphStartX").value); var graphEndX = parseFloat(document.getElementById("graphEndX").value); var stepSize = parseFloat(document.getElementById("stepSize").value); var resultDiv = document.getElementById("result"); resultDiv.innerHTML = ""; // Clear previous results // Input validation if (isNaN(boundary1) || isNaN(boundary2) || isNaN(graphStartX) || isNaN(graphEndX) || isNaN(stepSize)) { resultDiv.innerHTML = "Please enter valid numbers for all numerical inputs."; return; } if (graphStartX >= graphEndX) { resultDiv.innerHTML = "'Graph Start X' must be less than 'Graph End X'."; return; } if (stepSize = boundary2) { resultDiv.innerHTML = "'Boundary 1' must be less than 'Boundary 2'."; return; } var points = []; // Adjust loop to ensure graphEndX is included if stepSize allows for (var x = graphStartX; x <= graphEndX + (stepSize / 2); x += stepSize) { // Add stepSize/2 to handle floating point inaccuracies near end var y; if (x = boundary1 && x = boundary2 y = evaluateExpression(functionExpr3, x); } if (!isNaN(y)) { points.push({ x: x, y: y }); } else { // If an expression results in NaN (e.g., sqrt(-1)), note it points.push({ x: x, y: "Undefined" }); } } if (points.length === 0) { resultDiv.innerHTML = "No points generated. Check your range and step size."; return; } var tableHTML = ""; for (var i = 0; i < points.length; i++) { tableHTML += ""; } tableHTML += "
X ValueY Value
" + points[i].x.toFixed(4) + "" + (typeof points[i].y === 'number' ? points[i].y.toFixed(4) : points[i].y) + "
"; resultDiv.innerHTML = tableHTML; } .piecewise-graphing-calculator { font-family: Arial, sans-serif; background-color: #f9f9f9; padding: 20px; border-radius: 8px; max-width: 800px; margin: 20px auto; box-shadow: 0 2px 4px rgba(0,0,0,0.1); } .piecewise-graphing-calculator h2, .piecewise-graphing-calculator h3 { color: #333; text-align: center; margin-bottom: 15px; } .piecewise-graphing-calculator p { line-height: 1.6; margin-bottom: 10px; } .calculator-inputs label { display: inline-block; width: 200px; margin-bottom: 8px; font-weight: bold; } .calculator-inputs input[type="text"], .calculator-inputs input[type="number"] { width: calc(100% – 210px); padding: 8px; margin-bottom: 8px; border: 1px solid #ddd; border-radius: 4px; box-sizing: border-box; } .calculator-inputs button { display: block; width: 100%; padding: 10px 15px; background-color: #007bff; color: white; border: none; border-radius: 4px; font-size: 16px; cursor: pointer; margin-top: 15px; } .calculator-inputs button:hover { background-color: #0056b3; } .calculator-results { margin-top: 30px; border-top: 1px solid #eee; padding-top: 20px; } .calculator-results table { width: 100%; border-collapse: collapse; margin-top: 15px; } .calculator-results th, .calculator-results td { border: 1px solid #ddd; padding: 8px; text-align: center; } .calculator-results th { background-color: #f2f2f2; font-weight: bold; } .calculator-results tr:nth-child(even) { background-color: #f2f2f2; } .calculator-results tr:hover { background-color: #e9e9e9; } .calculator-results p { text-align: center; font-style: italic; color: #666; }

Understanding Piecewise Functions and How to Graph Them

A piecewise function is a function defined by multiple sub-functions, each applying to a different interval of the independent variable (usually 'x'). Instead of a single rule, a piecewise function uses different rules for different parts of its domain. This allows for functions that have sharp turns, jumps, or even breaks, making them incredibly versatile for modeling real-world phenomena.

Components of a Piecewise Function

Every piecewise function consists of two main parts for each 'piece':

  1. Function Expression: This is the mathematical rule (e.g., x^2, 2x + 1, 5) that determines the output (y-value) for a given input (x-value).
  2. Interval: This specifies the range of x-values for which that particular function expression is valid. Intervals are typically defined using inequalities (e.g., x < 0, 0 ≤ x < 2, x ≥ 2).

For example, consider the function:

f(x) = { x^2,       if x < 0
       { x,         if 0 ≤ x < 2
       { 4 - x,     if x ≥ 2

In this example:

  • For any x-value less than 0, the function behaves like x^2.
  • For x-values between 0 (inclusive) and 2 (exclusive), the function behaves like x.
  • For any x-value greater than or equal to 2, the function behaves like 4 - x.

How to Use the Piecewise Function Graphing Calculator

Our calculator simplifies the process of generating points for your piecewise function, which you can then use to manually plot or input into a dedicated graphing tool. Here's how to use it:

  1. Define Function Expressions: For each of the three available pieces, enter the mathematical expression. Remember to use * for multiplication (e.g., 2*x instead of 2x) and Math.pow(base, exponent) for powers (e.g., Math.pow(x, 2) for x^2). The calculator supports standard JavaScript Math functions like Math.sin(), Math.cos(), Math.sqrt(), etc.
  2. Set Boundaries (B1 and B2): These are the x-values where your function transitions from one expression to another. Ensure that Boundary 1 is less than Boundary 2.
  3. Specify Graphing Range:
    • Graph Start X: The lowest x-value for which you want to generate points.
    • Graph End X: The highest x-value for which you want to generate points.
  4. Choose Step Size: This determines how frequently the calculator will evaluate the function within your specified range. A smaller step size will generate more points, resulting in a smoother representation of the graph, but will also produce a longer table.
  5. Generate Points: Click the "Generate Points" button. The calculator will then display a table of (x, y) coordinates.

Interpreting the Results

The output is a table of x and corresponding y-values. Each y-value is calculated by applying the correct function expression based on the x-value's interval. You can use these points to:

  • Manually Plot: Draw these points on a coordinate plane and connect them within their respective intervals.
  • Input into Graphing Software: Many online graphing tools or spreadsheet programs allow you to input a list of (x, y) coordinates to visualize the graph.

Example Calculation

Let's use the example function mentioned above:

f(x) = { x^2,       if x < 0
       { x,         if 0 ≤ x < 2
       { 4 - x,     if x ≥ 2

To calculate points for this function from x = -3 to x = 5 with a step size of 0.5, you would input:

  • Function 1: Math.pow(x, 2)
  • Function 2: x
  • Function 3: 4 - x
  • Boundary 1 (B1): 0
  • Boundary 2 (B2): 2
  • Graph Start X: -3
  • Graph End X: 5
  • Step Size: 0.5

Clicking "Generate Points" would produce a table similar to this (partial table shown):

X ValueY Value
-3.00009.0000
-2.50006.2500
-2.00004.0000
-1.50002.2500
-1.00001.0000
-0.50000.2500
0.00000.0000
0.50000.5000
1.00001.0000
1.50001.5000
2.00002.0000
2.50001.5000
3.00001.0000
3.50000.5000
4.00000.0000
4.5000-0.5000
5.0000-1.0000

This table provides the discrete points needed to visualize the piecewise function's behavior across its defined intervals.

Note on Security: This calculator uses a JavaScript function constructor (new Function()) to evaluate the mathematical expressions you provide. While this is more controlled than a direct eval(), it still executes code. Only input expressions from trusted sources or expressions you understand. Malicious code could potentially be executed if untrusted input is used.

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