From fa080de7afc95aa1c19a6e6fc0e0708ced2eadc4 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 8 Jul 2015 20:46:52 -0400 Subject: Initial commit --- math/slalib/doc/fitxy.hlp | 76 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 76 insertions(+) create mode 100644 math/slalib/doc/fitxy.hlp (limited to 'math/slalib/doc/fitxy.hlp') diff --git a/math/slalib/doc/fitxy.hlp b/math/slalib/doc/fitxy.hlp new file mode 100644 index 00000000..814deb9f --- /dev/null +++ b/math/slalib/doc/fitxy.hlp @@ -0,0 +1,76 @@ +.help fitxy Jun99 "Slalib Package" +.nf + + SUBROUTINE slFTXY (ITYPE,NP,XYE,XYM,COEFFS,J) + + - - - - - - + F T X Y + - - - - - - + + Fit a linear model to relate two sets of [X,Y] coordinates. + + Given: + ITYPE i type of model: 4 or 6 (note 1) + NP i number of samples (note 2) + XYE d(2,np) expected [X,Y] for each sample + XYM d(2,np) measured [X,Y] for each sample + + Returned: + COEFFS d(6) coefficients of model (note 3) + J i status: 0 = OK + -1 = illegal ITYPE + -2 = insufficient data + -3 = singular solution + + Notes: + + 1) ITYPE, which must be either 4 or 6, selects the type of model + fitted. Both allowed ITYPE values produce a model COEFFS which + consists of six coefficients, namely the zero points and, for + each of XE and YE, the coefficient of XM and YM. For ITYPE=6, + all six coefficients are independent, modelling squash and shear + as well as origin, scale, and orientation. However, ITYPE=4 + selects the "solid body rotation" option; the model COEFFS + still consists of the same six coefficients, but now two of + them are used twice (appropriately signed). Origin, scale + and orientation are still modelled, but not squash or shear - + the units of X and Y have to be the same. + + 2) For NC=4, NP must be at least 2. For NC=6, NP must be at + least 3. + + 3) The model is returned in the array COEFFS. Naming the + elements of COEFFS as follows: + + COEFFS(1) = A + COEFFS(2) = B + COEFFS(3) = C + COEFFS(4) = D + COEFFS(5) = E + COEFFS(6) = F + + the model is: + + XE = A + B*XM + C*YM + YE = D + E*XM + F*YM + + For the "solid body rotation" option (ITYPE=4), the + magnitudes of B and F, and of C and E, are equal. The + signs of these coefficients depend on whether there is a + sign reversal between XE,YE and XM,YM; fits are performed + with and without a sign reversal and the best one chosen. + + 4) Error status values J=-1 and -2 leave COEFFS unchanged; + if J=-3 COEFFS may have been changed. + + See also slPXY, slINVF, slXYXY, slDCMF + + Called: slDMAT, slDMXV + + P.T.Wallace Starlink 11 February 1991 + + Copyright (C) 1995 Rutherford Appleton Laboratory + Copyright (C) 1995 Association of Universities for Research in Astronomy Inc. + +.fi +.endhelp -- cgit