C API Functions¶

create_qp_problem¶

qp_problem_t *create_qp_problem(
    const double *objective_c,
    const matrix_desc_t *Q_desc,
    const matrix_desc_t *R_desc,
    const matrix_desc_t *D_desc,
    const matrix_desc_t *A_desc,
    const double *con_lb, const double *con_ub,
    const double *var_lb, const double *var_ub,
    const double *objective_constant
);

Creates a QP problem of the form min 0.5 * x^T (Q + R^T D R) x + c^T x subject to con_lb <= A x <= con_ub and var_lb <= x <= var_ub.

Parameters:

Parameter	Description
`objective_c`	Linear objective coefficients (size n)
`Q_desc`	Sparse quadratic matrix descriptor (can be NULL)
`R_desc`	Low-rank factor descriptor, shape `k x n` (can be NULL)
`D_desc`	Middle matrix in `R^T D R`, shape `k x k` (can be NULL).
`A_desc`	Constraint matrix descriptor
`con_lb`	Constraint lower bounds (size m)
`con_ub`	Constraint upper bounds (size m)
`var_lb`	Variable lower bounds (size n)
`var_ub`	Variable upper bounds (size n)
`objective_constant`	Constant term in objective (can be NULL)

Returns: Pointer to allocated qp_problem_t, or NULL on error.

set_start_values¶

void set_start_values(
    qp_problem_t *prob,
    const double *primal,
    const double *dual
);

Sets initial primal and dual solutions for warm starting.

Parameters:

Parameter	Description
`prob`	QP problem pointer
`primal`	Primal solution vector (size n, can be NULL)
`dual`	Dual solution vector (size m, can be NULL)

solve_qp_problem¶

pdhcg_result_t *solve_qp_problem(
    const qp_problem_t *prob,
    const pdhg_parameters_t *params
);

Solves the QP problem using the PDHCG algorithm.

Parameters:

Parameter	Description
`prob`	QP problem pointer
`params`	Solver parameters

Returns: Pointer to pdhcg_result_t containing solution information.

solve_qp_problem_distributed¶

pdhcg_result_t *solve_qp_problem_distributed(
    const pdhg_parameters_t *params,
    const qp_problem_t *original_problem
);

Solves the QP problem using the distributed multi-GPU PDHCG algorithm.

Availability

This function is only available when PDHCG is compiled with -DPDHCG_COMPILE_DISTRIBUTED=ON.

Parameters:

Parameter	Description
`params`	Solver parameters (including `partition_method`, `permute_method`, `grid_size`, and `permute_block_size`)
`original_problem`	QP problem pointer (only required on rank 0; can be NULL on other ranks)

Returns: Pointer to pdhcg_result_t containing solution information (valid on all ranks; only rank 0 writes output).

set_default_parameters¶

void set_default_parameters(pdhg_parameters_t *params);

Fills the parameter struct with default values.

Parameters:

Parameter	Description
`params`	Pointer to parameters struct to fill

pdhcg_result_free¶

void pdhcg_result_free(pdhcg_result_t *results);

Frees memory allocated for the result structure.

Parameters:

Parameter	Description
`results`	Result pointer to free

qp_problem_free¶

void qp_problem_free(qp_problem_t *prob);

Frees memory allocated for the QP problem structure.

Parameters:

Parameter	Description
`prob`	Problem pointer to free