qhalf -- halfspace intersection about a point.  Qhull 2020.2 2020/08/31
    input (stdin): [dimension, 1, interior point]
                       dimension+1, number of halfspaces, coefficients+offset
    comments start with a non-numeric character

options (qhalf.htm):
    Hn,n - specify coordinates of interior point
    Qt   - triangulated output
    QJ   - joggled input instead of merged facets
    Tv   - verify result: structure, convexity, and redundancy
    .    - concise list of all options
    -    - one-line description of each option
    -?   - this message
    -V   - version

output options (subset):
    s    - summary of results (default)
    Fp   - intersection coordinates
    Fv   - non-redundant halfspaces incident to each intersection
    Fx   - non-redundant halfspaces
    G    - Geomview output (dual convex hull)
    m    - Mathematica output (dual convex hull)
    o    - OFF file format (dual convex hull)
    QVn  - print intersections for halfspace n, -n if not
    TI file - input file, may be enclosed in single quotes
    TO file - output file, may be enclosed in single quotes

examples:
    rbox d | qconvex FQ n | qhalf s H0,0,0 Fp
    rbox c | qconvex FQ FV n | qhalf s i
    rbox c | qconvex FQ FV n | qhalf s o