Experience with a high level language that supports interval arithmetic

An extension of the language S-algol⁴ called Triplex⁵ which facilitates the use of interval arithmetic and which is similar to triplex algol 60³ is described. Experience in the use of Triplex is reported. In particular, a Triplex program corresponding to a triplex algol 60 program of Nickel¹⁹ is given, together with numerical results.