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Diffstat (limited to 'math/llsq/g1.f')
| -rw-r--r-- | math/llsq/g1.f | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/math/llsq/g1.f b/math/llsq/g1.f new file mode 100644 index 00000000..5d44c50b --- /dev/null +++ b/math/llsq/g1.f @@ -0,0 +1,33 @@ + 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 |