UBASIC
UBASIC is a freeware BASIC interpreter written by Yuji Kida at Rikkyo University in Japan, specialized for mathematical computing.
Features
UBASIC is a ready-to-run language that does not need to be set up with another advanced language, which is a common problem with multi-digit math languages. It runs in DOS or in a DOS box under DOS shell, Microsoft Windows, etc. It is specialized for number theory, primality testing, factoring, and large integers (up to 2600 digits). Being an implementation of BASIC makes it easy to read programs without having to do extensive study, as BASIC is a language that has a structure and syntax close to ordinary algebra. The help files have articles and lessons for beginners.
UBASIC has a built-in on-line editor with several aids for debugging. It can show cross references to calling lines, lines containing a variable, and lists of variables/arrays. It can renumber lines, change variable names, and append additional programs. It can trace, single step, and time by milliseconds to help determine the fastest way to do highly repetitive sections. It can redefine function keys, either to provide an easy one-keypress function or to prevent a standard function from being accidentally used when it shouldn't. It can shell to DOS or execute a DOS command. It can convert between single-byte character set and double-byte character set, but to have much use for this, the host computer would likely need an aware operating system. Documents may be added to or modified in UBHELP.HLP.