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# MatCreateLMVMDFP
Creates a limited-memory Davidon-Fletcher-Powell (DFP) matrix used for approximating Jacobians. L-DFP is symmetric positive-definite by construction, and is the dual of L-BFGS where Y and S vectors swap roles. 
## Synopsis
```
#include "petscksp.h" 
PetscErrorCode MatCreateLMVMDFP(MPI_Comm comm, PetscInt n, PetscInt N, Mat *B)
```
To use the L-DFP matrix with other vector types, the matrix must be
created using `MatCreate()` and `MatSetType()`, followed by `MatLMVMAllocate()`.
This ensures that the internal storage and work vectors are duplicated from the
correct type of vector.

Collective


## Input Parameters

- ***comm -*** MPI communicator
- ***n -*** number of local rows for storage vectors
- ***N -*** global size of the storage vectors



## Output Parameter

- ***B -*** the matrix



## Options Database Keys

- ***-mat_lmvm_scale_type -*** (developer) type of scaling applied to J0 (none, scalar, diagonal)
- ***-mat_lmvm_theta -*** (developer) convex ratio between BFGS and DFP components of the diagonal J0 scaling
- ***-mat_lmvm_rho -*** (developer) update limiter for the J0 scaling
- ***-mat_lmvm_alpha -*** (developer) coefficient factor for the quadratic subproblem in J0 scaling
- ***-mat_lmvm_beta -*** (developer) exponential factor for the diagonal J0 scaling
- ***-mat_lmvm_sigma_hist -*** (developer) number of past updates to use in J0 scaling





## Note
It is recommended that one use the `MatCreate()`, `MatSetType()` and/or `MatSetFromOptions()`
paradigm instead of this routine directly.


## See Also
 [](ch_ksp), `MatCreate()`, `MATLMVM`, `MATLMVMDFP`, `MatCreateLMVMBFGS()`, `MatCreateLMVMSR1()`,
`MatCreateLMVMBrdn()`, `MatCreateLMVMBadBrdn()`, `MatCreateLMVMSymBrdn()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/utils/lmvm/dfp/dfp.c.html#MatCreateLMVMDFP">src/ksp/ksp/utils/lmvm/dfp/dfp.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/ksp/utils/lmvm/dfp/dfp.c)


[Index of all KSP routines](index.md)  
[Table of Contents for all manual pages](/manualpages/index.md)  
[Index of all manual pages](/manualpages/singleindex.md)