tests floating arithmetic by evaluating the sum of four numerical series
p1=20
70s10		clear 12, 10, 8, 6, 4
9s2
75sr-1

70s12		s = 12, becomes function part of add order
70t0		t = 0,  used to skip even terms in sum

26f1(98		F(4) = n, initially n = 1
18f4
14f4
19f2		F(2) = n^2
26f1
15f2
19f2		F(2) = 1/n^2

18f6		F(6) = sum 1/n^2
10f2
14f2
18f12		F(12) = sum 1/n^4

10f2
76t1024		skip alternate n
18f8		F(8) = sum 1/(2n+1)^2
72t1024

10f10		F(M) = sum so far (-1)^(n+1)/n^2
89sr1		store s as function part of next order
0f2		add or subtract term alternately
19f10		F(10) = sum including next term
3s0
70s25		set s = 25 - s, that is 12 and 13 alternately

10f2
13*1e-7
54p98		loop if 1/n^2 > 1e-7

110f1534	F(M) = pi/2
19f2
12f2
19f2
14f2
19f2		F(2) = pi^2

10f6		sum 1/n^2
59f29
10f2
15*6.0
59f29		pi^2/6
107f2		print cr
107f8		print lf

10f8		sum 1/(2n+1)^2
59f29
10f2
15*8.0
59f29		pi^2/8
107f2
107f8

10f10		sum (-1)^(n+1)/n^2
59f29
10f2
15*12.0
59f29		pi^2/12
107f2
107f8

10f12		sum 1/n^4
59f29
10f2
14f2
15*90.0
59f29		pi^4/90
101f0

s20