;+ ;FUNCTION: thm_cal_rot(v1,v2) ;INPUT: ; v1: 3 component vector, ; v2: 3 component vector, ;PURPOSE: ; Returns a rotation matrix that rotates v1,v2 to the x-y plane ; v1 is rotated to the x-axis and v2 into the x-y plane ;NOTES: ; Function normally called by "add_df2d.pro" to rotate ; velocities into the plane of Vsw and B ; ;CREATED BY: ; J.McFadden ;LAST MODIFICATION: ; 95-9-13 J.McFadden ;- function thm_cal_rot,v1,v2 a=v1/(total(v1^2))^.5 d=v2/(total(v2^2))^.5 c=crossp(a,d) c=c/(total(c^2))^.5 b=-crossp(a,c) b=b/(total(b^2))^.5 rotinv = dblarr(3,3) rotinv(0,*) = a rotinv(1,*) = b rotinv(2,*) = c rot = invert(rotinv) return, rot end