2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/157804The writhe of a space curve fragment is considered for various boundary conditions. An expression for the writhe as a function of arclength for an arbitrary space curve is obtained. The formula is built on the base of closing the tangent indicatrix with a geodesic. The corresponding closure of a curve in 3-space is explicitly constructed. The addition rule for writhe is formulated. A relationship connecting the writhe with the Gauss integral over the open curve is presented. The single and double regular helical shapes are examined as examples.56 pages, 9 figuresBiological Physicstext