Roots of a quadratic function: Difference between revisions

<br>(from a default of &nbsp; '''9''') &nbsp; to &nbsp; '''200''' &nbsp; to accommodate when a root is closer to zero than the other root.

Note that only ten decimal digits (precision) are shown in the &nbsp; ''displaying'' &nbsp; of the output.

rpr=1/(aa+aa); c ?=right($,1)=='i' /*compute reciprocal of 2*aa; Complex?*/

if c? then do; n=left($,L-1); r1= -bb*rp; *r; r2=r1; r1j=nleft($,L-1)*rpr; r2j=-r1j; end

else do; r1=(-bb+$)*rpr; r2=(-bb-$)*rpr; r1j=0; r1j=0; r2j= 0; end

sqrt: procedure; parse arg x 1 ox; if x=0 then return 0; d=digits(); i=; m.=9

numeric digits 9; numeric form; h=d+6; if x<0 then do; x=-abs(x; i='i'; end)

parse value format(x,2,1,,0) 'E0' with g 'E' _ .; g=g *.5'e'_ %2

do j=0 while h>9; m.j=h; h=h%2+1; end /*j*/

do k=j+5 to 0 by -1; numeric digits m.k; g=(g+x/g)*.5; end /*k*/

numeric digits d; return (g/1)left('i ',ox<0) /*make complex if X OX< 0.*/</lang>