;
; rta_tst0_pi_plouffe.rta
; =======================
;
; Pi computation by Plouffes formula. It is:
;
;                  4       2       1       1         n
; pi = summe    (----- - ----- - ----- - -----)(1/16)
;      [n=0..]   8*n+1   8*n+4   8*n+5   8*n+6
;
; Init
;
	_name	Pi
	clr	pi				; 0 to variable pi
	clr	restgl				; 0 to variable "restgl"
	mov	n	-1			; -1 to variable n
	mov	8n	-8			; -8 to variable "-8"
	mov	1/16	0.0625			; 0.0625 to variable "1/16"
	mov	f1	16			; 16 to f1 ...
	cls					; "clear screen": clear output text area
	pause	Pi~Formula~of~Plouffe~... 	; user message
;
; The Loop
;
loop:
	add	n	1			; cycle counter (not needed)
	add	8n	8			; the variable 8n is 8*n
	mov	z1	4			
	mov	n1	8n
	add	n1	1
	div	z1	n1			; 1st term
	mov	z2	2
	mov	n2	8n
	add	n2	4
	div	z2	n2			; 2nd term
	mov	z3	1
	mov	n3	8n
	add	n3	5
	div	z3	n3			; 3rd term
	mov	z4	1
	mov	n4	8n
	add	n4	6
	div	z4	n4			; 4th term
	mul	f1	1/16			; 1/16 power n
	clr	restgl				; 			
	add	restgl	z1
	sub	restgl	z2
	sub	restgl	z3
	sub	restgl	z4
	mul	restgl	f1			; new summand
	add	pi	restgl			; add to pi
	printn	n	4	0		; output ...
	prints	:~				; of : and a space
	printn	pi	1	18		; of pi with 1.18 digits
	prints	\				; output of a newline
	mov	absx	restgl
	abs	absx
	output	pi	Continue~...		; Cyclic dialog
	cmpgt	absx	1E-18	loop		; gt: new loop
	save	rta_pi
	output	pi	Computation~finished.~Result~is~also~written~into~file~rta_pi.txt.
	exit					
	_end