From the unix operating system to access **ez_fit** as a stand alone program by entering :

ezfit

In order to access **ez_fit** from other IDL program, a user has to make
sure that the following environment variable is set before invoking IDL :

setenv EPICS_EXTENSIONS /usr/local/epics/extensions

and make sure including the directory **/usr/local/epics/extensions/idllib**
in his/her IDL search path.

- COMFITGRAF
- CURVEFITGRAF
- EZ_FIT
- GAUSSFITGRAF
- LADFITGRAF
- LINFITGRAF
- LORENTZFITGRAF
- LORENTZIAN_CURVE
- MULTI_LORENTZFITGRAF
- POLYFITGRAF
- POLYFITWGRAF
- READASCII
- REGRESSFIT
- REGRESSGRAF

NAME: COMFITGRAF PURPOSE: This routine packages the IDL gradient-expansion least square fit COMFIT function to fit the paired data {x(i), y(i)}. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: COMFITGRAF, X, Y [,A] [,YFIT] [,SIGMA] ,/FIT_TYPE [,/PRINT] [,/TEST] INPUTS: X: Position X vector of type integer, float or double. Y: Data value Y vector of type integer, float or double. A: Optional input, initial estimates of fitting coefficients. Number of elements in A depends on the FIT_TYPE specified. If A given, the number of elements in A must be consistant with the FIT_TYPE entered. KEYWORD PARAMETERS: FIT_TYPE: Six type of COMFIT, it can be any of following EXPONENTIAL Y = a0 * a1^x + a2 GEOMETRIC Y = a0 * x^a1 + a2 GOMPERTZ Y = a0 * a1^(a2*x) + a3 HYPERBOLIC Y = 1./(a0 + a1*x) LOGISTIC Y = 1./(a0 * a1^x + a2) LOGSQUARE Y = a0 + a1*alog10(x) + a2 * alog10(x)^2 PRINT: Specifies whether the output window will be poped up. TEST: Specifies whether the default test data will be used. OPTIONAL OUTPUTS: YFIT: Y vector calculated from the fitted equation. SIGMA: Standard deviation for the parameters in A. SIDE EFFECTS: The computed parameters and the convergence may depend on the data and the initial parameters of A vector entered. RESTRICTIONS: The number of parameters must match exactly to the FIT_TYPE specified. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: Run the geometric fitting, and pops up the fitting result window X = [ ...] Y = [ ...] A = [ 0.5, 0.5, 0.5] COMFITGRAF,X,Y,A,/GEOMETRIC,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 08-13-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: CURVEFITGRAF PURPOSE: Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: CURVEFITGRAF,X,Y,Weights [,A ] [,Sigma] [,/PRINT] $ [,FUNCTION_NAME='funct'] $ [,/NODERIVATIVE] [,ITMAX=20] [,TOL=1.e-3] INPUTS: X: Position X vector Y: Data value Y vector Weights: A row vector of weights, the same length as Y. Defaults to 1. Instrumental weighting-Gaussian : Weights(i) = 1./sigma(i) ^2 Statistical weighting-Poisson : Weights(i) = 1./y(i) A: The coefficients of the fit. The number of elements in A must be exactly the same as that defined in the function_name. If not specified, the fitting function should provide the initial default. KEYWORD PARAMETERS: PRINT: Specifies whether the output window will be poped up. FUNCTION_NAME: The name of the procedure function to fit. If omitted, NODERIVATIVE: If this keyword is set then the partial derivatives will be calculated by CURVEFIT by forward differences. Otherwise the procedure function should provide the partial derivatives calculation. Defaults nodevivative is not set. The procedure function must be written as in 'FUNCT' as described in IDL 'CURVEFIT' restrictions. ITMAX: Maximum number of iterations. Default = 20. TOL: The convergence tolerance. Default = 1.e-3. The routine returns when the relative decrease in chi-squared is less than TOL. OPTIONAL OUTPUTS: A: Returns the coefficients of the fit. Sigma: A vector of standard deviations for the parameters in A. RESTRICTIONS: The function to be fit must be defined and called FUNCT, unless the FUNCTION_NAME keyword is supplied. This function, (actually written as a procedure) must accept values of X (the independent variable), and A (the fitted function's parameter values), and return F (the function's value at X), and PDER (a 2D array of partial derivatives). For an example, see FUNCT in the IDL User's Libaray. A call to FUNCT is entered as: FUNCT, X, A, F, PDER where: X = Variable passed into CURVEFIT. It is the job of the user-written function to interpret this variable. A = Vector of NTERMS function parameters, input. F = Vector of NPOINT values of function, y(i) = funct(x), output. PDER = Array, (NPOINT, NTERMS), of partial derivatives of funct. PDER(I,J) = DErivative of function at ith point with respect to jth parameter. Optional output parameter. PDER should not be calculated if the parameter is not supplied in call. If the /NODERIVATIVE keyword is set in the call to CURVEFIT then the user routine will never need to calculate PDER. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. For more information please refer the PROCEDURE section of the CURVEFIT in IDL online help. EXAMPLE: X = [ ...] Y = [ ...] CURVEFITGRAF,X,Y,Weights,A,Sigma,/PRINT For more information please refer the EXAMPLE section of the CURVEFIT in IDL online help. MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-15-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: EZ_FIT PURPOSE: This routine integrates all the IDL line fitting routines into one single package. It provides the IDL user with a very easy to use line fitting tool. It is a standalone widget application. It can be easily plug into any other IDL program. It accepts 1D or 2D arrays either from the input binary file or directly from the command line. It also accepts the spreadsheet column type ascii input file. It allows the user to select any vector from the input data and perform any fitting he/she desires. It lets the user easily get the hardcopy of fitting graph and tabulated data. CATEGORY: Curve fitting Widgets application. CALLING SEQUENCE: EZ_FIT KEYWORD PARAMETERS: XARRAY: Specifies the independent varialbe X vector if input to be entered from the command line. YARRAY: Specifies the dependent varialbe Y array if input to be entered from the command line. It is used by 1D or 2D data. For 2D image data, the YARRAY represents the Y vector of the second dimension. For 1D data, multiple data vectors can be packed into Y array. The Y(N,M), the N must have the same dimension as in X vector. the M represents the number of dependent variables in Y array. A user can use the cursor in the image area to select the dependent variable to be fitted, or use the J text field to specify the dependent variable to be fitted.. IM: Specifies the 2D image array corresponding to XARRAY and YARRAY. IMAGE(N,M), where dimenstion N is the same as the number of elements in XARRAY, M is the same as the number of elements in YARRAY. IPICK: Specifies the row # from the Y array or 2D image array to be fitted initially. JPICK: Specifies the column # from the Y array or 2D image array to be fitted initially. JPICK supercedes IPICK. INPATH: Specifies the initial search path GROUP: The widget ID of the group leader of the widget. If this keyword is specified, the death of the group leader results in the death of EZ_FIT. OUTPUTS: Pops up plot and list window to show fitting results with respect to the input data. COMMON BLOCKS: COMMON EZ_FIT_BLOCK,ezfitData,image SIDE EFFECTS: It uses the PLOT1D and XDISPLAYFILE program to show the fitting results. RESTRICTIONS: Input binary file must be created by the U_OPERW and U_WRITE rountines. The input data is in platform independent XDR binary format. Default input file filter for 1D data is '*.bin1d', the default input file filter for 2D data is '*.bin'. User may override this default setting in the file selection dialog. Input 1D file should contains only two binary objects XARRAY and YARRAY. Input 2D file should contains only 3 binary objects XARRAY YARRAY and IMAGE. Input ASCII type file should contain columns of input data. It uses the W_READASCII to read in columns of data. The first column will be independent variable, the remaining columns will be dependent variables. EXAMPLE: Example 1 - Use the File->Open to load input data EZ_FIT Example 2 - Use the X,Y keywords to load 1D data EZ_FIT,XARRAY=X, YARRAY=Y Example 3 - Use the keywords to load 2D data EZ_FIT,XARRAY=X, YARRAY=Y, IM=image MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 09-12-97. 02-27-98 Inherit color tables from the calling program 10-04-99 Incooporate the FUNCT_ERF fit to curvefitgraf 10-18-99 Add the support of weight factor 01-06-00 Add the support of jpick, and ipick for image array 01-23-02 Upgrade the readascii user interface for 1D/2D data 03-01-02 R1.6 Modify multiple Lorenzian ROI user interface 04-30-02 Fix GetData menu features with fittin.bin data Handle the case where the table_size is less than 256

**(See ez_fit.pro)**

NAME: GAUSSFITGRAF PURPOSE: This routine uses the IDL GAUSSIAN fit function y=f(x) where: F(x) = A0*EXP(-z^2/2) + A3 + A4*x + A5*x^2 and z=(x-A1)/A2 A0 = height of exp, A1 = center of exp, A2 = sigma (the width). A3 = constant term, A4 = linear term, A5 = quadratic term. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: GAUSSFITGRAF,X,Y [,A ] [,ESTIMATES=extimates] [,NTERMS=nterms] [,/PRINT] INPUTS: X: Position X vector Y: Data value Y vector KEYWORD PARAMETERS: ESTIMATES: Optional starting estimates for the parameters of the equation. Should contain NTERMS (6 if NTERMS is not provided) elements. NTERMS: Set NTERMS of parameters used in Gaussian fit. PRINT: Specifies whether the output window will be poped up. OPTIONAL OUTPUTS: A: The coefficients of the fit. A is a three to six element vector as described under PURPOSE. RESTRICTIONS: The peak or minimum of the Gaussian must be the largest or smallest point in the Y vector. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] GAUSSFITGRAF,X,Y,NTERMS=4,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-03-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: LADFITGRAF PURPOSE: This routine uses the IDL LADFIT function to fit the paired data {x(i), y(i)} with the linear model Y = A + Bx. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: LADFITGRAF, X, Y [,YFIT] [,ABSDEV=absdev] [,/DOUBLE] [,/PRINT] [,/TEST] INPUTS: X: Position X vector Y: Data value Y vector KEYWORD PARAMETERS: ABSDEV: Specifies whether the mean absolute deviation to be returned. PRINT: Specifies whether the output window will be poped up. TEST: Specifies whether the default test data will be used. DOUBLE: If set to a non-zero value, computations are done in double precision arithmetic. OPTIONAL OUTPUTS: YFIT: Y vector calculated from the fitted equation. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] LADFITGRAF,X,Y,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 08-13-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: LINFITGRAF PURPOSE: This routine uses the IDL LINFIT function to fit the paired data {x(i), y(i)} with the linear model Y = A + Bx. It minimize the chi-square error statistic. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: LINFITGRAF, X, Y [,YFIT] [,CHISQ=chisq] [,PROG=prob] [,SDEV=sdev] [,SIGMA=sigma] [,/DOUBLE] [,/PRINT] [,/TEST] INPUTS: X: Position X vector Y: Data value Y vector KEYWORD PARAMETERS: CHISQ: Use this keyword to specify a named variable which returns the chi-square error statistic as the sum of squared errors between Y(i) and A + BX(i). If individual standard deviations are supplied, then the chi-square error statistic is computed as the sum of squared errors divided by the standard deviations. PROB: Use this keyword to specify a named variable which returns the probability that the computed fit would have a value of CHISQR or greater. If PROB is greater than 0.1, the model parameters are "believable". If PROB is less than 0.1, the accuracy of the model parameters is questionable. SDEV: An n-element vector of type integer, float or double that specifies the individual standard deviations for {X(i), Y(i)}. SIGMA: Use this keyword to specify a named variable which returns a two-element vector of probable uncertainties for the model par- ameters, [SIG_A,SIG_B]. PRINT: Specifies whether the output window will be poped up. TEST: Specifies whether the default test data will be used. DOUBLE: If set to a non-zero value, computations are done in double precision arithmetic. OPTIONAL OUTPUTS: YFIT: Y vector calculated from the fitted equation. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] LINFITGRAF,X,Y,sigma=sigma,chisq=chisq,prob=prob,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 08-13-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: LORENTZFITGRAF PURPOSE: This routine uses the CURVEFIT function with the non-linear fitting function_name='lorentzian' specified. y=f(x) where: F(X) = A0 * A2^2 / ((X-A1)^2 + A2^2) and A0 = height of exp, A1 = center of exp, A2 = FWHM/2 Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: LORENTZFITGRAF, X, Y [,A] [,/PRINT] [,YFIT=yfit] INPUTS: X: Position X vector of type float or double. Y: Data value Y vector of type float or double. A: Optional input [A0,A1,A2], initial estimates of fitting coefficients. KEYWORD PARAMETERS: PRINT: Specifies whether the output window will be poped up. YFIT: Y vector calculated from the fitted equation. SIDE EFFECTS: The computed parameters and the convergence may depend on the data and the initial parameters of A vector entered. RESTRICTIONS: The number of parameters must be three. The initial value should be close to the real data value with: A0 = height of exp, A1 = center of exp, A2 = FWHM/2 Especially the center of expectation must corresponds to the peak of the lorentzian. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: Run the geometric fitting, and pops up the fitting result window X = [ ...] Y = [ ...] A = [ Peak, Mean, FWHM/2 ] LORENTZFITGRAF,X,Y,A,/GEOMETRIC,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-15-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: LORENTZIAN_CURVE PURPOSE: For a given set of lorentzian parameters [a0,a1,a2], this routine calculate the corresponding {y(i)} for a given set of {x(i)}. CATEGORY: Fitted data with plot. CALLING SEQUENCE: LORENTZIAN_CURVE, A, X, Y [,/PLOT] INPUTS: A: Fitted lorentzian coefficients, [A0,A1,A2]. X: Position X vector of type float or double. Y: Data value Y vector of type float or double. KEYWORD PARAMETERS: PLOT: Specifies whether to plot the Y vector. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: Run the geometric fitting, and pops up the fitting result window X = [ ...] A = [Peak, Mean, FWHM/2] LORENTZIAN_CURVE,A,X,Y,/PLOT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-15-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: MULTI_LORENTZFITGRAF PURPOSE: This routine uses the CURVEFIT function to fit a set of multiple LORENTZIAN functions y=f(x) where: F(X) = A0 * A2^2 / ((X-A1)^2 + A2^2) + ... and A0 = height of exp, A1 = center of exp, A2 = FWHM/2 Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: MULTI_LORENTZFITGRAF, X, Y, A [,YFIT=yfit] [,/PRINT] [,/SUBPLOT] INPUTS: X: Position X vector of type float or double. Y: Data value Y vector of type float or double. A: Lorentzian coefficients vector. It consists of a set of multiple of 3 parameters for each lorentzian. [ [A0,A1,A2], [A0,A1,A2], ... ] KEYWORD PARAMETERS: YFIT: Y vector calculated from the fitted lorentzian equations. PRINT: Specifies whether the output window will be poped up. SUBPLOT: If specified, a plot window shows the composition of all the multiple lorentzian curves. SIDE EFFECTS: The computed parameters and the convergence may depend on the data and the initial parameters of A vector entered. RESTRICTIONS: The number of parameters must be multiple of 3. The initial value should be close to the real data value with: A0 = height of exp, A1 = center of exp, A2 = FWHM/2 Especially the center of expectation must corresponds to each local peak of the lorentzian. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: Run the geometric fitting, and pops up the fitting result window X = [ ...] Y = [ ...] A = [ Peak1, Mean1, FWHM1/2, Peak2, Mean2, FWHM2/2, ... ] MULTI_LORENTZFITGRAF,X,Y,A,/GEOMETRIC,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-15-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: POLYFITGRAF PURPOSE: This routine uses the IDL least square polynomial fit function PLOYFIT with optional error estimates. Double precision computation is assumed. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: POLYFITGRAF,X,Y,NDEGREE [,A ] [,YFIT] [,YBAND] [,SIGMA] [,CORRM] [,/PRINT] INPUTS: X: Position X vector Y: Data value Y vector NDEGREE: The degree of polynomial to fit. KEYWORD PARAMETERS: PRINT: Specifies whether the output window will be poped up. OPTIONAL OUTPUTS: A: Correlation matrix of the coefficients. YFIT: The vector of calculated Y's. Has an error of + or - Yband. YBAND: Error estimate for each point = 1 sigma. SIGMA: The standard deviation in Y units. CORRM: The correlation matrix of the coefficients. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] POLYFITGRAF,X,Y,4,A,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-03-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: POLYFITWGRAF PURPOSE: This routine uses the IDL least square polynomial fit function PLOYFITW with optional error estimates. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: POLYFITWGRAF,X,Y,W,NDEGREE [,A ] [,YFIT] [,YBAND] [,SIGMA] [,/PRINT] INPUTS: X: Position X vector Y: Data value Y vector W: The vector of weights. This vector should be same length as X and Y. NDEGREE: The degree of polynomial to fit. KEYWORD PARAMETERS: PRINT: Specifies whether the output window will be poped up. OPTIONAL OUTPUTS: A: Correlation matrix of the coefficients. YFIT: The vector of calculated Y's. Has an error of + or - Yband. YBAND: Error estimate for each point = 1 sigma. SIGMA: The standard deviation in Y units. PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] POLYFITWGRAF,X,Y,W,4,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 10-03-97. xx-xx-xxbkc comment

**(See ez_fit.pro)**

NAME: READASCII PURPOSE: Read data from an ASCII file into an array. It is assumed that each line with same number of entries. It can extract a sub-rectangle of region from the ascii file. CATEGORY: Input/Output CALLING SEQUENCE: READASCII, Filename, Rarray, X, Y [ /DOUBLE, SKIP=skip, LINES=lines, L_COLUMN=l_column, COLUMNS=columns , XCOL=xcol ] INPUT: Filename - Input file name KEYWORD PARAMETERS: DOUBLE - specifies output variable in double position SKIP - skip number of lines at beginning of file LINES - total number of lines to be read L_COLUMN - skip number of columns from the input line COLUMNS - total number of columns to be read from the line XCOL - specifies the X axis column number, defualt 0 YROW - specifies the Y axis column number, defualt 3 for 2D array OUTPUTS: Rarray - Return the dependent variable columns read in X - Return the column as X independent variable Y - Return dependent variable(s) for 1D data Return the Y independent variable for 2D data RESTRICTIONS: The input file must be in ASCII form. The header lines must be placed at the beginning of the file. They can be skipped by setting the SKIP equal to the number of header lines at beginning. Each data line must contains the exactly same number of columns. EXAMPLE: READASCII, 'Filename', RARRAY, X, Y MODIFICATION HISTORY: Written by: Ben-chin K. Cha 09-16-98 bkc Allows blank lines at end of ascii file, no blank lines allowed between data 11-23-99 bkc Use keyword XCOL to specify the column to be used as X-axis 01-23-02 bkc Use keyword YROW to specify the line to be used as Y-axis ( only used by 2D data array) 07-15-02 bkc Move drawing area cursor event to top

**(See ez_fit.pro)**

NAME: REGRESSFIT PURPOSE: Linear regression fitting program allows the user to calibrate the data and call the IDL REGRESS function to get the linear regression fitting to find A0, A1, and A2 Yi = A0 + A1 * Xi1 + A2 * Xi2 for all i The sample data can be loaded into REGRESSFIT from an ASCII file. The fitting plot and fitting report can be generated from this program. CATEGORY: Widgets. CALLING SEQUENCE: REGRESSFIT [,X,Y] [,GROUP=Group] INPUTS: X[2,NPT]: The independent variable [Xi1,Xi2] corresponding to Yi Y[NPT]: The dependent variable Yi where NPT is the total number of data point. KEYWORD PARAMETERS: GROUP: If specified, the close of parent window will close this regressfit window. SIDE EFFECTS: If no X, Y data arrays are specified on the command line, then the default sample data from the IDL reference book is initially assumed. RESTRICTIONS: The fitting.rpt... is shared by all fitting methods. If the fitting result is desired, it must be pressed before committing the next fitting method. EXAMPLES: regressfit MODIFICATION HISTORY: Written by: Ben-chin K. Cha, Mar. 7, 2002.

**(See ez_fit.pro)**

NAME: REGRESSGRAF PURPOSE: This routine uses the IDL multiple linear regression fit function REGRESS with optional weighting vector specification estimates. Then calls PLOT1D to graph the calculated results with the raw data in a pop-up window. CATEGORY: Curve fitting with plot. CALLING SEQUENCE: REGRESSGRAF,X,Y,W [,YFIT] [,A0] [,SIGMA] [,FTEST] [,R] [,RMUL] [,Chisq] [,Status] [,/Relative_weight] [,/PRINT] [Group=group] INPUTS: X: Position X vector Y: Data value Y vector W: The vector of weights. This vector should be same length as Y. KEYWORD PARAMETERS: PRINT: Specifies whether the output window will be poped up. RELATIVE_WEIGHT: If specified no weighting is desired OPTIONAL OUTPUTS: YFIT: The vector of calculated Y's. Has an error of + or - Yband. A0: Returns the constant item. SIGMA: The standard deviation in Y units. FTEST: Returns the value of F for test of fit. R: Returns the vector of linear correlation coefficents. RMUL: Returns the multiple linear correlation coefficient. CHISQ: Returns the reduced, weighted chi-squared STATUS: Returns the status of internal array inversion computation. 0-successful, 1-singular, 2-small pivot point PROCEDURE: Before accessing this routine, the 'ez_fit.pro' must be loaded into IDL and the path to 'ez_fit.pro' must be in the IDL search path. EXAMPLE: X = [ ...] Y = [ ...] REGRESSGRAF,X,Y,W,YFIT,A0,/PRINT MODIFICATION HISTORY: Written by: Ben-chin K. Cha, 03-01-02. xx-xx-xxbkc comment

**(See ez_fit.pro)**