Enter a mathematical function and a value for 'x' to evaluate the function at that point. This tool simulates a core aspect of a graphing calculator by calculating specific function outputs.
function calculateFunction() {
var functionString = document.getElementById("functionString").value;
var xValue = parseFloat(document.getElementById("xValue").value);
var resultDisplay = document.getElementById("resultDisplay");
if (isNaN(xValue)) {
resultDisplay.innerHTML = "Please enter a valid number for x.";
return;
}
if (!functionString.trim()) {
resultDisplay.innerHTML = "Please enter a function.";
return;
}
// Pre-process the function string for common math operations and syntax
// Note: Using eval() can be risky with untrusted input. For this client-side calculator,
// where the user inputs the function, it's used for simplicity.
var processedFunction = functionString
.replace(/(\d+)x/g, "$1*x") // e.g., 2x -> 2*x
.replace(/x(\d+)/g, "x*$1") // e.g., x2 -> x*2
.replace(/\^/g, "**") // Use JavaScript's exponentiation operator
.replace(/PI/g, "Math.PI")
.replace(/E/g, "Math.E")
.replace(/sin\((.*?)\)/g, "Math.sin($1)")
.replace(/cos\((.*?)\)/g, "Math.cos($1)")
.replace(/tan\((.*?)\)/g, "Math.tan($1)")
.replace(/log\((.*?)\)/g, "Math.log($1)") // Natural logarithm (base e)
.replace(/log10\((.*?)\)/g, "Math.log10($1)") // Base 10 logarithm
.replace(/sqrt\((.*?)\)/g, "Math.sqrt($1)")
.replace(/abs\((.*?)\)/g, "Math.abs($1)")
.replace(/round\((.*?)\)/g, "Math.round($1)")
.replace(/ceil\((.*?)\)/g, "Math.ceil($1)")
.replace(/floor\((.*?)\)/g, "Math.floor($1)");
// Define x in the scope for eval
var x = xValue;
var result;
try {
result = eval(processedFunction);
if (isNaN(result)) {
resultDisplay.innerHTML = "Error: Invalid function or calculation resulted in NaN. Check your function syntax.";
} else if (!isFinite(result)) {
resultDisplay.innerHTML = "Error: Calculation resulted in Infinity or -Infinity. Check for division by zero or invalid operations.";
}
else {
resultDisplay.innerHTML = "f(" + xValue + ") = " + result.toFixed(6); // Format to 6 decimal places
}
} catch (e) {
resultDisplay.innerHTML = "Error evaluating function: " + e.message + ". Please check your function syntax.";
}
}
.calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 500px;
margin: 30px auto;
border: 1px solid #e0e0e0;
}
.calculator-container h2 {
text-align: center;
color: #333;
margin-bottom: 20px;
font-size: 1.8em;
}
.calculator-container p {
color: #555;
text-align: center;
margin-bottom: 25px;
line-height: 1.6;
}
.calculator-input {
margin-bottom: 18px;
display: flex;
flex-direction: column;
}
.calculator-input label {
margin-bottom: 8px;
color: #333;
font-weight: bold;
font-size: 1em;
}
.calculator-input input[type="text"],
.calculator-input input[type="number"] {
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 1em;
width: 100%;
box-sizing: border-box;
transition: border-color 0.3s ease;
}
.calculator-input input[type="text"]:focus,
.calculator-input input[type="number"]:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}
button {
background-color: #007bff;
color: white;
padding: 12px 25px;
border: none;
border-radius: 6px;
cursor: pointer;
font-size: 1.1em;
font-weight: bold;
width: 100%;
box-sizing: border-box;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 15px;
}
button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
button:active {
transform: translateY(0);
}
.calculator-result {
margin-top: 25px;
padding: 15px;
background-color: #e9f7ff;
border: 1px solid #cce5ff;
border-radius: 8px;
font-size: 1.2em;
color: #004085;
text-align: center;
font-weight: bold;
word-wrap: break-word;
}
Understanding Your Function Evaluator
A graphing calculator is an indispensable tool for students, engineers, and anyone working with mathematical functions. While a full graphing calculator app can display complex visual representations of functions, this simplified "Function Evaluator" focuses on a core capability: calculating the output of a function for a specific input value.
What Does This Calculator Do?
This tool allows you to input any mathematical function, such as f(x) = x^2 + 2x + 1, and then specify a numerical value for x. It will then compute and display the exact output of that function at your chosen x value. This is incredibly useful for checking specific points on a graph, verifying calculations, or understanding function behavior without needing to draw the entire graph.
How to Use the Function Evaluator
Enter Your Function: In the "Function f(x) =" field, type your mathematical expression. Use x as your variable.
Specify 'x' Value: In the "Value for x:" field, enter the number at which you want to evaluate your function.
Evaluate: Click the "Evaluate Function" button. The result, f(x), will appear below.
Supported Operations and Syntax
This evaluator supports a wide range of standard mathematical operations and functions. Here's a guide to the syntax:
This tool is a function evaluator, not a full graphing calculator. It will not display a visual graph of your function. Its purpose is to provide precise numerical outputs for specific input values, which is a fundamental step in understanding and analyzing functions.