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Parametric derivative is a derivative in calculus that is taken when both the ''x'' and ''y'' variables (traditionally independent and dependent, respectively) depend on an independent third variable ''t'', usually thought of as "time". ==Example== For example, consider the set of functions where: : and : The first derivative of the parametric equations above is given by: : where the notation denotes the derivative of ''x'' with respect to ''t'', for example. To understand why the derivative appears in this way, recall the chain rule for derivatives: : or in other words : More formally, by the chain rule: and dividing both sides by gets the equation above. Differentiating both functions with respect to ''t'' leads to : and : respectively. Substituting these into the formula for the parametric derivative, we obtain : where and are understood to be functions of ''t''. The second derivative of a parametric equation is given by : | |- | | |- | | |} by making use of the quotient rule for derivatives. The latter result is useful in the computation of curvature. 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Parametric derivative」の詳細全文を読む スポンサード リンク
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