Vector Differentiation

     As with functions of one variable we define the derivative as the limit of a difference quotient.

Definition (Difference Quotient) The difference quotient of a vector function is the vector function:

vector differentiation _gr_1.gif]

where vector differentiation _gr_2.gif] is a change of the variable vector differentiation _gr_3.gif]

Definition (Derivative of a Vector Function) The derivative of a vector function vector differentiation _gr_4.gif] is the vector function vector differentiation _gr_5.gif] defined as the limit

vector differentiation _gr_6.gif]

provided this limit exists.

Proposition (Derivative of a Vector Function) The vector function

vector differentiation _gr_7.gif]

is differentiable whenever the component functions vector differentiation _gr_8.gif], vector differentiation _gr_9.gif], and vector differentiation _gr_10.gif] are each differentiable and in this case vector differentiation _gr_11.gif]

    Proof. By the definition of the derivative of a vector function,

vector differentiation _gr_12.gif]

vector differentiation _gr_13.gif]

Using properties of limits of vector functions and the fact that the component functions vector differentiation _gr_14.gif], vector differentiation _gr_15.gif], and vector differentiation _gr_16.gif] are each differentiable we have,  

vector differentiation _gr_17.gif]

   vector differentiation _gr_18.gif]

Example (Derivative of a Vector Function) Find the derivative of the vector function

vector differentiation _gr_19.gif]

    Solution. The derivative is the vector function  

vector differentiation _gr_20.gif]
vector differentiation _gr_21.gif]

Cite this as:
Vector Differentiation
Published by Library of Math -- Online math organized by subject into topics.
Written by Smith, David A.
http://www.libraryofmath.com/vector-differentiation.html
 
    
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