Once I tried to write a DEC Fortran program to solve a quadratic the high school way, the exact formula you know -b+/- sqrt(b^2 ...., I got a ridiculous answer, so I tried a numeric routine from the DEC collection and wow was that wrong! So I programmed my own numeric routine and that worked. Meanwhile, I used my HP xx scientific calculator. I can't remember the precision, but the answer was bang-on. They do have their uses...