I can't help but love these HP scientific calculators. The HP-32S is another finely crafted engineering marvel. It's fast, it does just about everything a scientific calculator is expected to do, it has enough memory for storing fairly complex programs. It fits in a shirt pocket, runs forever on three watch batteries, and has that rugged feel that HP instruments are so famous for.

Unfortunately, the HP-32S is also a calculator no longer made by Hewlett-Packard. The good news is that a replacement model (HP-32SII) is still being sold in stores.

The programming model of the HP-32S is very similar to that of the HP-42S. It's keystroke programming; program steps are displayed on the calculator's alphanumeric display in mnemonic form. The calculator's 390-byte memory is dynamically divided up between programs and variables; up to 26 named variables can be used, and they are automatically deallocated when their value is set to 0.

Just as a scientific calculator of its class should, the HP-32S has its built-in version of the Gamma function (or to be precise, it provides an extended factorial function that accepts any real argument except negative integers.) On the other hand, the HP-32S has built-in support for complex numbers. This support is not as well integrated as it is with the HP-42S or even the HP-15C (it is necessary to prefix operators with the CMPLX button which makes it a bit cumbersome to write programs that can operate on both complex and real arguments), but it's fairly complete; in addition to complex arithmetic operators, the complex versions of transcendental and trigonometric functions are also implemented. Which makes a complex version of the Gamma function an excellent programming example demonstrating the capabilities of this calculator.

The program below is just that, a Gamma function program that accepts any complex argument for which the function's value is defined. To use, enter the imaginary part of the argument, hit ENTER, enter the real part, then hit XEQ G.

G01	LBL G
G02	1
G03	STO G
G04	CLx
G05	STO H
G06	Rv
J01	LBL J
J02	x>0?
J03	GTO H
J04	RCL H
J05	RCL G
J06	CMPLX×
J07	STO G
J08	Rv
J09	STO H
J10	Rv
J11	1
J12	+
J13	GTO J
H01	LBL H
H02	STO A
H03	x<>y
H04	STO B
H05	x<>y
H06	0
H07	2.50662827511
H08	CMPLX×
H09	0
H10	83.8676043424
H11	CMPLX+
H12	RCL B
H13	RCL A
H14	CMPLX×
H15	0
H16	1168.92649479
H17	CMPLX+
H18	RCL B
H19	RCL A
H20	CMPLX×
H21	0
H22	8687.24529705
H23	CMPLX+
H24	RCL B
H25	RCL A
H26	CMPLX×
H27	0
H28	36308.2951477
H29	CMPLX+
H30	RCL B
H31	RCL A
H32	CMPLX×
H33	0
H34	80916.6278952
H35	CMPLX+
H36	RCL B
H37	RCL A
H38	CMPLX×
H39	0
H40	75122.633153
H41	CMPLX+
H42	0.006
H43	STO i
H44	Rv
I01	LBL I
I02	RCL B
I03	RCL i
I04	IP
I05	RCL+ A
I06	CMPLX÷
I07	ISG i
I08	GTO I
I09	STO X
I10	x<>y
I11	STO Y
I12	RCL B
I13	5.5
I14	RCL+ A
I15	RCL B
I16	0.5
I17	RCL+ A
I18	CMPLXyx
I19	RCL B
I20	5.5
I21	RCL+ A
I22	CMPLX+/-
I23	CMPLXex
I24	CMPLX×
I25	RCL Y
I26	RCL X
I27	CMPLX×
I28	RCL H
I29	RCL G
I30	CMPLX÷
I31	RTN