HP 40gs - Page 249

Computer Algebra System (CAS) 14-67
Typing:
gives:
LAP See ILAP above.
PA2B2 Decomposes a prime integer p congruent to 1 modulo 4,
as follows:
p = a
2
+ b
2
.
The calculator gives the result as a + b · i.
Example 1
Typing:
PA2B2(17)
gives:
4 + i
that is, 17 = 4
2
+ 1
2
Example 2
Typing:
PA2B2(29)
gives:
5 + 2 · i
that is, 29 = 5
2
+ 2
2
PSI Returns the value of the nth derivative of the Digamma
function at a.
The Digamma function is the derivative of ln(Γ(x)).
Example
Typing:
PSI(3, 1)
I
LAP
1
X
2
6X–9+
----------------------------
X 6–()ab+⋅+
X
2
6X–9+
-------------------------------------------------------------------
⎝
⎠
⎜
⎟
⎜
⎟
⎜
⎟
⎛
⎞
x
3
6
-----
3ab–()– xa+⋅
⎝⎠
⎛⎞
e
3x
⋅
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