HP 49g+, Руководство пользователя, Страница: 85 / 862

Page 2-30
Derivatives
We will use the Equation Writer to enter the following derivative:
) (
2
δ β α + ⋅ + ⋅
t t
dt
d
Press
‚O
to activate the Equation Writer. Then press
‚¿
to enter
the (partial) derivative sign. Notice that the sign, when entered into the
Equation Writer screen, provides input locations for the expression being
differentiated and the variable of differentiation. To fill these input locations,
use the following keystrokes:
~„t™~‚a*~„tQ2
™™+~‚b*~„t+~‚d
The resulting screen is the following:
To see the corresponding expression in the line editor, press
‚—
and the
A
soft menu key, to show:
This indicates that the general expression for a derivative in the line editor or
in the stack is:
∂ variable
(
function of variables
)
Press
`
to return to the Equation Writer. The resulting screen is not the
derivative we entered, however, but its symbolic value, namely,
To recover the derivative expression use
‚¯
. To evaluate the derivative
again, you can use the
D
soft menu key. This shows again that