Fixed cathetus
A divisor of the square of a prescribed leg determines the corresponding integral Pythagorean triangle.

Scientific foundation
The technology is grounded in Roberto Amato's published work on divisor-based Pythagorean parametrization, primitive triples, algebraic structures, prime characterization and congruent-number elliptic curves.
Divisor parameter and inradius
Let x > 1 be an odd integer. For this odd case, an admissible parameter d is a positive divisor of x² satisfying d < x. Each such divisor determines a nondegenerate integral right triangle with fixed odd leg x:
Here d is not an arbitrary geometric length: it is the divisor parameter selecting a member of the fixed-cathetus Pythagorean family. The inradius r of that triangle satisfies
In the canonical specialization d = 1, this becomes
This is the relation used by the Pythagorean Sieve.
Congruent-number curve
The area N of a rational right triangle leads, through the classical triangle–curve correspondence, to a rational point on the congruent-number elliptic curve
The divisor-based parametrization therefore associates admissible pairs (x,d) with explicit pointed elliptic curves. For odd x, the uniqueness of the admissible divisor d = 1 is equivalent to the corresponding elementary primality criterion.
Research thread
A divisor of the square of a prescribed leg determines the corresponding integral Pythagorean triangle.
The relation between the divisor parameter and the inradius yields the arithmetic indexing used by the sieve.
For odd x, primality becomes a uniqueness statement for the admissible divisor family.
Explicit Pythagorean triangles lead to distinguished rational and integral points on congruent-number curves.
Selected number-theory publications
Public records
Technical brochure