Hey, I've been having an issue. I need to set up a Newton Raphson method for approximating an answer to an equation, line after line for many conditions. The purpose of setting up this function has been that I am solving a complex math problem that has weird answers and I need to arrive at a real solution, and I need to do so more quickly than the solver or goalseek functions have been able to do for me. Which works! The newton raphson method is WAY faster for one line in my case, so that's not the issue. Long story short, I have one line/row of my spreadsheet completely solved and it solves the equation I need lightning fast. To do so, I have 2 functions set up as the equation I have simplified my problem to and a function for its derivative to perform a taylor-series like iterative solution within a 3rd function, which I call out below those. A sub calls out the third function, which calls the first and second, and the line becomes solved and outputs a cell where my answer should be. My original plan was to solve everything for one line, and use a simple for loop (which would be easy in any other program *ahem Matlab) to loop through that function for 1 to 2 to 3 etc rows down, and have the functions grab cells from the line that the for loop is running on. Setting up a for loop inside of each cell obviously won't work, and the variable I loop through, "j", can't be referenced within the other functions if I call it out within the sub, where it needs to be. I want to call out, for example, b = Cells(j, "CJ") in the function that the sub calls, and have the sub be a big for loop that changes j... I HAVE GOT AROUND my problem by making a for loop that inside my sub fills up a column in the spreadsheet with 1's, and in my functions I set j equal to a command that counts the number of cells filled in the column range, but since it has to output cells and count rows it takes too long for the size of data I need it for (like 50 lines.) Is there ANY way to reference a variable, WITHIN A CHANGING FOR LOOP, inside of a function that you call out? will global variables work? (I've tried global variables but can't set one up that changes where I need it to.) PLEASE FOR THE LOVE OF GOD help me, I'm going insane trying to find an answer, all I've found on threads is basic for loop help and referencing things within subs, but nothing that quite helps. Any help would be appreciated, let me know if I'm supposed to/it would be helpful to paste my code somewhere. Thanks in advance!