Lagrange's notation for differentiation
Lagrange's notation for differentiation is the
notation for
differentiation devised by
Joseph Louis Lagrange. Lagrange proposed the notations:
- f''(x) for the first derivative
- f''(x) for the second derivative
- f'''(x) for the third derivative
- f(n)(x) for the nth derivative (n > 3)
It is done this way as for high numbers of derivatives the number of primes will be come cumbersome to write.
Expressed in terms of Leibniz's notation for differentiation we have:
-
-
and so on.
Sometimes Lagrange's notation is more useful than Leibniz's, for example when calculating the derivative at a point.
In Lagrange's notation, if you know f(x) and you want to calculate f '(x) at a point k, you would write:
and this represents that
derivative. For example, if
f(
x) =
x2, then
f '(3) = 6. The same thing under Leibniz's notation is more cumbersome:
Leibniz's notation is versatile in that it allows you to specify the variable for differentiation (in the denominator). This is especially relevant for
partial differentiation.