1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
|
subroutine g1 (a,b,cos,sin,sig)
c c.l.lawson and r.j.hanson, jet propulsion laboratory, 1973 jun 12
c to appear in 'solving least squares problems', prentice-hall, 1974
c
c
c compute orthogonal rotation matrix..
c compute.. matrix (c, s) so that (c, s)(a) = (sqrt(a**2+b**2))
c (-s,c) (-s,c)(b) ( 0 )
c compute sig = sqrt(a**2+b**2)
c sig is computed last to allow for the possibility that
c sig may be in the same location as a or b .
c
zero=0.
one=1.
if (abs(a).le.abs(b)) go to 10
xr=b/a
yr=sqrt(one+xr**2)
cos=sign(one/yr,a)
sin=cos*xr
sig=abs(a)*yr
return
10 if (b) 20,30,20
20 xr=a/b
yr=sqrt(one+xr**2)
sin=sign(one/yr,b)
cos=sin*xr
sig=abs(b)*yr
return
30 sig=zero
cos=zero
sin=one
return
end
|
