Okay, so using GNU 2.95.2 I was able to get my LM algorithm to compile. I have levmrq (which is my main file), and mrqmin, mrqcof, gaussj, and covsrt written as is from the NumRec in C++ book. I also have copied down the nrutil.h, nr.h, nrtypes.h header files from the book as is. I can compile and link the codes but when I run it I get a segmentation error from my nrutil.h code line 142. I am new to C++ and am trying to figure this out on my own but I am amazingly stuck. I copied everything verbatim from the book and I dont know how to fix this problem. I know people barely reply on this forum but if you have gotten your program to work at least let me know if I am missing something because obviously I am. Can you send me an example file of a working mrqmin system (roshoge@ncsu.edu) with all the files you used. That would help me greatly!! Thanks yall :)

i figured it out with example book