Formula and functions

//
// To see the graphics output of this macro, click  here 
// Here we create a Canvas named "c1" with all default parameters
//
gROOT.Reset(c1)
TCanvas c1(c1)
//
// We create a formula object and compute the value of this formula
// for two different values of the x variable.
//
TFormula form1(form1,sqrt(abs(x)))
form1.Eval(2)
form1.Eval(-45)
//
// Create a one dimensional function and draw it
//
TF1 fun1(fun1,abs(sin(x)/x),0,10)
c1.SetGridx
c1.SetGridy
fun1.Draw
//
// Before leaving this demo, we print the list of objects known to ROOT
// using the command "?" and also some statistics.
//
?
gObjectTable.Print
exit

//----------------------------------------------------------------------
// The log file from this macro is shown below
//
Root >  exec formula1.mac
virtual Double_t  = 1.41421
virtual Double_t  = 6.7082

Root >  ?
 ======> Dynamic objects defined = 13
   TROOT        < gROOT>          The ROOT Interactive Interface
   TGXW         < gGXW>           ROOT interface to X11
   TPostScript  < ps>             Default PostScript object
   TStyles      < gStyle>                 Default Style
   TObjectTable < gObjectTable>   Table of active objects
   TClassTable  < gClassTable>    Table of known classes
   TMinuit      < gMinuit>        The Minimization package
   TUnixSystem  < gSystem>        Unix System
   TEnv         < gEnv>           System configuration
   TFile        < f2>             Demo ROOT file with histograms
   TCanvas      < c1>             
   TFormula     < form1>          sqrt(abs(x))
   TF1          < fun1>           abs(sin(x)/x)

Root >  gObjectTable.Print
Object statistics
class                     cnt    on heap     size    total size    heap size
============================================================================
TROOT                       1          0    20176         20176            0
TFile                       1          1      132           132          132
TList                    2147       2147       36         77292        77292
TDirectory                  1          1       88            88           88
TCanvas                     1          1      440           440          440
TF1                         1          1     1784          1784         1784
TGaxis                      1          0      120           120            0
TStyles                     1          1      364           364          364
TClass                     73         73       76          5548         5548
TGXW                        1          1      172           172          172
TPostScript                 1          1      764           764          764
TObjectTable                1          1       12            12           12
TClassTable                 1          1       12            12           12
TMinuit                     1          1    62680         62680        62680
TUnixSystem                 1          1      252           252          252
TSignalHandler              1          1       20            20           20
TEnv                        1          1       24            24           24
TOrdCollection              3          3       40           120          120
TFormula                    1          1     1728          1728         1728
TMethodArg               2203       2203       44         96932        96932
TMethod                  1909       1909       56        106904       106904
TDataMember               596        596       44         26224        26224
TBaseClass                 81         81       36          2916         2916
TDynamic                   13         13       56           728          728
TKey                       33         33       64          2112         2112
TColor                    160        160       40          6400         6400
TMotifGuiFactory            1          1       28            28           28
TGeometry                   1          1       64            64           64
THashList                   4          4       40           160          160
THashTable                  4          4       36           144          144
TStopwatch                  1          0       56            56            0
TDataType                  33         33       56          1848         1848
TEnvRec                     6          6       48           288          288
TGlobal                    18         18       36           648          648
----------------------------------------------------------------------------
Total:                   7302       7299    89624        417180       396828
============================================================================