En hommage à Joseph-Louis Lagrange et à Pierre Huard

The contributions to science of Joseph-Louis Lagrange (or Giuseppe Luigi Lagrangia, since after all, even though of French descent, he was born in Torino!) are too many for me to list and even more, to comprehend. Like a number of other intellectual giants of the 18th and 19th century, he was familiar with most branches of science, and few people today can boast such breadth and depth of knowledge. His influence on many branches of mathematics is still profound. And yet, if it had not been for his father's unhealthy financial situation, he might have chosen to spend his time differently; he is quoted as saying ‘If I had been rich, I probably would not have devoted myself to mathematics’. After mentally thanking his father for his unsuccessful speculations, I will limit my homage to his study of ‘extrema liés’, i.e., extrema of functions of several variables subject to equality constraints, and by extension to inequality constraints, and of so-called Lagrangean multipliers, as they relate to my own research.