# NAG CL Interfacee04ryc (handle_​print)

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## 1Purpose

e04ryc is a part of the NAG optimization modelling suite. It allows you to print information about the problem, stored as a handle, such as which parts have already been defined or details of the constraints.

## 2Specification

 #include
 void e04ryc (void *handle, Nag_FileID fileid, const char *cmdstr, NagError *fail)
The function may be called by the names: e04ryc or nag_opt_handle_print.

## 3Description

e04ryc prints information on a problem handle which has been previously correctly initialized (e.g., by e04rac). Various pieces of information can be retrieved and printed to the given output unit. This can be helpful when the function is interfaced from interactive environments, for debugging purposes or to help familiarize you with the NAG optimization modelling suite.
The printer is guided by a command string which contains one or more of the following keywords:
Overview
Gives a brief overview of the problem handle, particularly, the problem dimension and which parts of the problem have already been set.
Objective
Prints the objective function as it was defined by e04rec, e04rfc, e04rsc or e04rtc when it is linear or quadratic. Prints the sparsity structure of the objective function as it was defined by e04rgc when it is nonlinear or nonlinear least squares by e04rmc.
Simple bounds
Prints the variable bounds as defined by e04rhc. This might help you understand the effect of the optional parameter ${\mathbf{Infinite Bound Size}}$ on the bounds.
Linear constraints bounds
Linear constraints detailed
Prints the bounds or the linear constraint matrix as defined by e04rjc.
Prints all the quadratic constraints including all nonzeros of quadratic, linear and constant terms as defined by e04rsc and e04rtc.
Cone constraints
Cone constraints detailed
Prints all second-order cone constraints as defined by e04rbc. For each cone constraint, its idgroup, dimension and type are printed. If details are requested, the variables composing the cone constraint are also listed.
Matrix constraints
Gives a list of the matrix constraints as defined by e04rnc and e04rpc. For each matrix constraint its idblk, dimension and order (e.g., linear, bilinear) are printed.
Matrix constraints detailed
Prints all the matrix constraints including all nonzeros of all the matrices as formulated by e04rnc and e04rpc.
Nonlinear constraints bounds
Nonlinear constraints detailed
Prints the bounds or sparsity structure of the nonlinear constraints as defined by e04rkc.
Multipliers sizes
Prints the expected dimensions of arrays storing the Lagrangian multipliers, such as u and ua of the solver e04svc which store the Lagrangian multipliers for standard and matrix constraints, respectively. This might be helpful with Overview and Matrix constraints to check the way the sizes of the arrays are derived.
Options
Options solver
Prints all the current optional parameters. It flags whether the argument is set to its default, whether you have set it or whether it is chosen by the solver (for example, options left on ‘AUTO’ setting after the solver has been called). In addition, you can print optional parameters belonging to a specific solver by adding the solver name after Options, e.g., keywords Options e04mt or Options handle_solve_lp_ipm print options only belonging to the linear programming solver e04mtc.
Note that the output data might not match your input exactly. The sparse matrices are typically transposed, sorted and explicit zeros removed and in certain cases transformed as needed (for example, matrices ${Q}_{ij}$ and ${Q}_{ji}$ are merged by e04rpc).
See Section 4.1 in the E04 Chapter Introduction for more details about the NAG optimization modelling suite.

None.

## 5Arguments

1: $\mathbf{handle}$void * Input
On entry: the handle to the problem. It needs to be initialized (e.g., by e04rac) and must not be changed between calls to the NAG optimization modelling suite.
2: $\mathbf{fileid}$Nag_FileID Input
On entry: the identifier associated with the file (or standard output) to be written to, as returned by a call of x04acc.
Constraint: ${\mathbf{fileid}}\ge 0$.
3: $\mathbf{cmdstr}$const char * Input
On entry: a command string which contains one or more keywords which identify the piece of information about the handle to be printed. Keywords are case-insensitive and space tolerant. Multiple keywords in cmdstr must be separated by commas or semicolons.
Constraint: cmdstr can only contain one or more of the following accepted keywords: overview, objective, simple bounds, linear constraints bounds, linear constraints detailed, matrix constraints, matrix constraints detailed, nonlinear constraints bounds, nonlinear constraints detailed, multipliers sizes, options.
4: $\mathbf{fail}$NagError * Input/Output
The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

## 6Error Indicators and Warnings

NE_ALLOC_FAIL
Dynamic memory allocation failed.
See Section 3.1.2 in the Introduction to the NAG Library CL Interface for further information.
On entry, argument $⟨\mathit{\text{value}}⟩$ had an illegal value.
NE_FILEID
On entry, ${\mathbf{fileid}}=⟨\mathit{\text{value}}⟩$.
Constraint: ${\mathbf{fileid}}\ge 0$.
NE_HANDLE
The supplied handle does not define a valid handle to the data structure for the NAG optimization modelling suite. It has not been properly initialized or it has been corrupted.
NE_INTERNAL_ERROR
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG for assistance.
See Section 7.5 in the Introduction to the NAG Library CL Interface for further information.
NE_NO_LICENCE
Your licence key may have expired or may not have been installed correctly.
See Section 8 in the Introduction to the NAG Library CL Interface for further information.
NE_STR_UNKNOWN
cmdstr does not contain any keywords or is empty.
Keyword number $⟨\mathit{\text{value}}⟩$ is not recognized.
Keyword number $⟨\mathit{\text{value}}⟩$ is not recognized, it is too long.
NE_WRITE_ERROR
An error occurred when writing to output.

Not applicable.

## 8Parallelism and Performance

e04ryc is not threaded in any implementation.

None.

## 10Example

This example shows the life-cycle of a handle of a typical (BMI-SDP) problem by printing the overview of the handle in various stages of the problem formulation and after the solution is found. It is also helpful to notice how a linear matrix inequality is extended with the bilinear term, see e04rac and e04rpc for further details.
The problem is as follows:
 $minimize x,y​ ​∈​ ​ℝ y subject to ( 1 x-1 y x-1 3/4 0 y 0 16 ) ⪰0 ( x -xy -xy 1 ) ⪰0 x≥0 -3≤y≤3$
The solution is $x=1/4$, $y=-2$.
Note that the matrix constraints need to be supplied in the form of equation (3) in e04rpc, i.e.,
 $∑ i,j=1 n xi xj Qijk + ∑ i=1 n xi Aik - A0k ⪰ 0 , k=1,…,mA .$
Therefore, the first constraint is defined by matrices
 $A 0 1 = ( -1 1 0 -3/4 0 -16 ) , A 1 1 = ( 0 1 0 0 0 0 ) , A 2 1 = ( 0 0 1 0 0 0 )$
and the second one by
 $A 0 2 = ( 0 0 -1 ) , A 1 2 = ( 1 0 0 ) , A 2 2 ​ empty, Q 12 2 = ( 0 -1 0 0 ) .$