# Excellent evidence that Gauß was right #
MODE L = LONG LONG REAL;
PROC (L)L rt = long long sqrt;
L r17 = rt(17);
L rx = rt(34 - 2*r17);
L cos = (-1 + r17 + rx + 2*rt(17 + 3*r17 - rx  - 2*rt(34 + 2*r17)))/16;
PROC p = (STRING s, L x)VOID: print((x, " ", s, newline));
p("r17", r17); p("cos(2π/17)", cos);
# cos is the cosine of 2π/17. #
L sin = rt(1 - cos*cos); p("sin", sin);
MODE LC = LONG LONG COMPL;
LC an = (cos, sin);
LC an2 = an*an, an4 = an2*an2, an8 = an4*an4, an17 = an8*an8*an;
print((an17, " an17", newline))
#
+4.12310562561766054982140985597407702514719922537362043439863357e  +0 r17
+9.32472229404355804573115891821563386262587777945116928248350012e  -1 cos(2π/17)
+3.61241666187152948744714596183700163724501384066052541465614556e  -1 sin
+1.00000000000000000000000000000000000000000000000000000000000000e  +0 -2.51610347408693624432000000000000000000000000000000000000000000e -64 an17
#