Function gemm_map_unchecked_with 

pub unsafe fn gemm_map_unchecked_with<T: MapScalar>(
    ws: &mut Workspace,
    m: usize,
    k: usize,
    n: usize,
    alpha: T,
    a: *const T,
    rsa: isize,
    csa: isize,
    b: *const T,
    rsb: isize,
    csb: isize,
    beta: T,
    c: *mut T,
    rsc: isize,
    csc: isize,
    f: &(dyn Fn(T, usize, usize) -> T + Sync),
    par: Parallelism,
)

Available on crate feature epilogue only.

Like gemm_map_unchecked but reuses a caller-owned Workspace instead of the thread-local pool

Safety

See gemm_map_unchecked