>Is any current language 100 times better than FORTRAN for programmer productivity, just as FORTRAN was compared to machine-code programming? Probably not.

I beg to differ. A well-designed Lisp, with the power of homoiconity (code-as-data, real macros), immutability by default and a sane model for concurrency. Running on the most optimized virtual machines (JVM, .NET CLR, JavaScript), with the ability to use all of their existing libraries.

I'm talking about Clojure.

http://clojure.org

http://clojurescript.org

How productive is a Clojure programmer when the requirement is to write a high -performance application which performs vector operations on large matrices?

You can be pretty productive.

Have a look at core.matrix (https://github.com/mikera/core.matrix) and vectorz.clj (https://github.com/mikera/vectorz-clj) libs. They give you almost native speeds.

If you need even more performance, checkout neanderthal (https://github.com/uncomplicate/neanderthal) which has a GPU back-end.