ECCONV Converts between eccentricity measures. Y=ECCONV(X,STR) converts the eccentricity measure X into eccentricity measure Y as specified by the string STR. STR is of the form 'in2out' where the names 'in' and 'out' may be chosen from the following table. STR Name Definition ---------------------------------------------------------------- 'ecc' Eccentricity sgn(b)*sqrt(1-b^2/a^2) 'ell' Ellipticity b/a 'lin' Linearity sgn(b)*(a^2-b^2)/(a^2+b^2) 'circ' Circularity 2ab/(a^2+b^2) 'nu' Eccentricity angle asin(b/sqrt(a^2 + b^2)) 'rot' Rotary ratio sgn(b)*(a-abs(b))/(a+abs(b)) where "a" and "b" are the semi-major and semi-minor axes respective. For example, ECC=ECCONV(L,'lin2ecc') converts the ellipse linearity L into eccentricity ECC. All quantities are positive for mathematically positive rotation and negative for mathematically negative rotation. Note the linearity is undefined for the case of purely circular rotation a=abs(b); For further details, see Lilly and Gascard (2006). ____________________________________________________________________ Cell array input/output If ECCONV is given cell array input, it returns cell array output. Thus X may be a cell arrays of numerical arrays, and the output Y will also be a cell array having an identical size as X. ____________________________________________________________________ See also ELLCONV, ELLDIFF, TRANSCONV. Usage: lin=ecconv(b./a,'ell2lin'); ecc=ecconv(lin,'lin2ecc'); 'ecconv --t' runs a test. 'ecconv --f' generates a sample figure. _________________________________________________________________ This is part of JLAB --- type 'help jlab' for more information (C) 2005--2015 J.M. Lilly --- type 'help jlab_license' for details