Casio fx-991ES Calculator User Manual


 
E-36
k Differential Calculations
Your calculator performs differential calculations by approximating
the derivative based on centered difference approximation.
d/dx( f(x), a, tol
)
f(x): Function of X (All non-X variables are treated as
constants.)
a: Input a value to specify the point for which the derivative
should be obtained (differential point)
tol:Tolerance range (input/output format: Linear)
•You can omit specification of the tolerance range. A default value
of 1 × 10
–10
is used when you do.
(, d/dx(, Pol(, Rec(, and Σ( cannot be used within f(x), a, or tol.
•Differential calculations can be performed in the COMP Mode only.
•When performing a differential calculation involving trigonometric
functions, specify Rad as the calculator’s default angle unit.
•A “Time Out” error occurs when a differential calculation ends
without the ending condition being fulfilled.
•A smaller tol value provides better precision, but it also causes
the calculation to take more time. Specify a tol value that is 1 ×
10
–14
or greater.
•You cannot input a tol value when using Math format.
• Inaccurate results and errors can be caused by the following :
- discontinuous points in x values
-extreme changes in x values
- inclusion of the local maximum point and local minimum point in
x values
- inclusion of the inflection point in x values
- inclusion of undifferentiable points in x values
- differential calculation results approaching zero
•Pressing A will interrupt an ongoing differential calculation.
Appendix
<#033> Determine f ’( ) when f(x) = sin(x)
(tol specification omitted.)
<#034> (3x
2
– 5x + 2, 2, 1×10
–12
) = 7
π
2
d
dx