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    Calculus (University Level)

    Directional Derivative

    Compute the directional derivative of f(x,y) = ax²y² in direction (u₁, u₂) at (x₀, y₀).

    Standard Formula
    Dᵤf = ∇f · û

    Interactive Sandbox

    Live Reactive

    Adjust values in real-time and observe mathematical cause-and-effect

    x0
    0.120
    y0
    120
    u1
    0.120
    u2
    0.120
    Live EquationFormula Proof
    Dᵤf = ∇f · û = 8.4853
    f'(x) slope
    Tangent Line dy/dx
    Calculated Solution
    8.4853

    Direct computational model evaluating Directional Derivative.

    Variable Mechanics

    Roles, constraints & impacts

    4 Params
    x0

    x-coordinate

    x-coordinate

    ImpactPrimary formula parameter
    ConstraintReal number
    y0

    y-coordinate

    y-coordinate

    ImpactPrimary formula parameter
    ConstraintReal number
    u1

    Direction vector component u₁

    Direction vector component u₁

    ImpactPrimary formula parameter
    ConstraintReal number
    u2

    Direction vector component u₂

    Direction vector component u₂

    ImpactPrimary formula parameter
    ConstraintReal number

    At a Glance

    Gotchas, units & real-world use

    Essential

    Formula Nature & Mechanics

    Direct computational model evaluating Directional Derivative.

    Common Mistakes & Traps

    • Ensure all input measurements share consistent units before calculating.
    • Check for denominator values approaching zero to prevent undefined division.
    • Follow standard order of operations (PEMDAS: Parentheses, Exponents, Multiply/Divide, Add/Subtract).

    Dimensional Analysis & Units

    Direct evaluation matching formula variable dimensions.

    Real-World & Industry Application

    Widely utilized across modern calculus applications, academic analysis, and engineering estimations.

    📖 Beginner's guideDirectional Derivative: Formula and ExamplesLearn how to find a directional derivative with Dᵤf = ∇f · û, why you must use a unit vector, and try the free calculator with step-by-step solutions.

    Worked Example: Directional Derivative

    Given:

    • x0 = 1
    • y0 = 2
    • u1 = 1
    • u2 = 1
    1. f=x²y², ∂f/∂x=2xy², ∂f/∂y=2x²y
    2. ∇f at (1,2)=(8,4)
    3. û=(1/√2,1/√2)
    4. Dᵤf=8/√2+4/√2 ≈ 8.485

    Answer: 8.4853

    Frequently Asked Questions

    What is the Directional Derivative formula?

    Dᵤf = ∇f · û. Compute the directional derivative of f(x,y) = ax²y² in direction (u₁, u₂) at (x₀, y₀).

    How do I calculate Directional Derivative?

    Enter x-coordinate (x0), y-coordinate (y0), Direction vector component u₁ (u1), Direction vector component u₂ (u2) into the calculator. It applies Dᵤf = ∇f · û and shows every step of the working.

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