This program computes COSH(Z) where Z is complex.

Argument entry: angle(Z) ENTER |Z| (so Y-reg = angle of Z in deg, X-reg = mag(Z))

Returns X-reg = mag(COSH(Z)) and Y-reg = angle of COSH(Z) in degrees.

The pgm changes registers 06,07,08,09, and the whole stack.

Implements Euler's definition of COSH(Z) = COSH(x + jy) = [(e^x * e^jy) + (e^-x * e^-jy)] / 2

and we say (e^x * e^jy) = a + jb, and (e^-x * e^-jy) = c + jd.

LBL COSHZ ; name of pgm

P-R ; get X=x

STO 06 ; save x

RDN

57.29578

* ; get y in degrees

STO 07

ENTER ; get Y-reg = y

RCL 06 ; get X-reg = x

e^x ; now X-reg = e^x

P-R ; now X-reg = a, Y-reg = b

STO 08 ; save a

RDN

STO 09 ; save b

RCL 07 ; get X-reg = y (still in degrees)

CHS ; we need (-y)

ENTER ; get it in Y-reg

RCL 06 ; get X-reg = x

CHS ; need (-x)

e^x ; get e^-x

P-R ; now X-reg = c, and Y-reg = d

RCL 08 ; get a

+ ; compute a+c

STO 06 ; save it

RDN ; now X-reg = d

RCL 09 ; get b

+ ; compute b+d

STO 07 ; save it. Now just get the result in polar form

RCL 06 ; now Y-reg = (b+d) and X-reg = (a+b)

R-P ; convert to polar form

2 ; don't forget to divide the mag by 2!

/

END ; end with COSH(Z) magnitude in X-reg and angle (in deg) in Y-reg.