"jInvert-Input.txt: for use in jInvert-Demo.exe", !any intro. <= 79 characters
  3,                  !Width & height of the complex matrix to be inverted.
 -1,                  !Rank of the matrix. <= -1 :compute it; >0 :known value
  1, 1, (  +0.100,  +0.000),
  1, 2, (  +0.100,  +1.000),
  1, 3, (  +1.000,  +0.000),
  2, 1, (  +2.000,  +0.000),
  2, 2, (  +0.100,  +0.000),
  2, 3, (  +0.100,  -2.000),
  3, 1, (  +0.100,  +0.000),
  3, 2, (  -4.000,  +0.000),
  3, 3, (  +0.100,  +0.000),
/                                      !<-Ends of the read by jInvert-Demo.exe
                     ^^^^^:Imaginary part- of the complex number
            ^^^^^:Real part              -  "  "     "       "
     ^:Column index
  ^:Row index
          
 The complex coefficients can be listed in any order.
   Omitted elements are assigned complex value zero.
 Trailing commas simplify reading by spreadsheets.

Both "jCin" and "jCinv" are printed out by jInvert.f95, & include:
   The actual rank.                                            -and- 
   All the coefficients in row-major order, comma separated.   -and-
   At full resolution (30+ digit complex components).

"jCin" shows what complex matrix jInvert() actually received.
-----------------------------------------------------
2026.04.19 JMS

The syntax above: "(_,_)" is interpreted by Fortran 95 as a complex number.
The ".csv" extension stands for "comma separated value", long used
by spreadsheets for reading & writing data.

For at least a few years, spreadsheets have had "COMPLEX" functionality.
(I have no experience using complex numbers in spreadsheets .) I have 
learned the following:

If you use spreadsheets as input files or outputs files:
  Be certain that the accuracy of your data isn't discarded by
  unrequested &/or unexpected roundoffs of values after the decimal point.
       
Fortran's type real(16) variables have 30-digit precision, no matter where
  the decimal point is within the number.
