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--- optim:userguide [2019/06/19 11:43]
helene
+++ optim:userguide [2022/05/27 10:05] (current)
helene [Activation of Lagamine Inverse]
@@ Line 1: / Line 1: @@
 ====== Optim user guide ======
+----
 ===== Lagamine Inverse =====
 The Lagamine Inverse code allows the computation of parameter sensitivity through a semi-analytical calculation. This implementation does not fundamentally change the code, but the simulation with Lagamine Inverse will be made so as to obtain both a reference finite element curve and the derivative of this curve with respect to the specified parameters. \\ To compute the derivative of the curve with respect to parameters, Lagamine will run one reference simulation with the input parameters and 2 additional simulations for each optimized parameter: one with a positive and on with a negative perturbation applied to the parameter (see [[optim:start#Description|OPTIM Description]]). \\ The values of the reference curve and its derivatives are put in a *.sm file at each iteration. When the Lagamine Inverse is used, the parameters specified by the user in the [[optim:files#*.ia file|*.ia file]] are not read from the *.lag file but from the [[optim:files#*.op file|*.op file]]. \\ \\
@@ Line 6: / Line 10: @@
   - Implementation in the Lagamine subroutines INVA.F and WSENSM.F to specify the finite element curves to use;
   - Creation of [[optim:files#*.ia file|*.ia file]] and [[optim:files#*.op file|*.op file]] indicating the number of finite element curve, the parameters to be optimized, their initial values, ...
+----
 ==== Activation of Lagamine Inverse ====
-In the *ex.dat file, the parameter IOPT (ninth parameter on the first line) must be set to 1 to activate the Lagamine Inverse simulation. It is also necessary to indicate an IDENT (5th parameter of first line) that allows the user to specify his curve in INVA.F and WSENSM.F (see <imgref image1>).
+In the *ex.dat file, the parameter IOPT (ninth parameter on the first line) must be set to 1 to activate the Lagamine Inverse simulation. It is also necessary to indicate an IDENT (5th parameter of first line) that allows the user to specify his curve in INVA.F and WSENSM.F (see <imgref image1>). For the list of existing IDENT, see [[optim:ident|this page]].
 <imgcaption image1|Example of *ex.dat file with activation of Lagamine Inverse>{{ :optim:optim_laginv1.png?600 |}}</imgcaption>
+----
 ==== Implementation of the curves in INVA.F ====
@@ Line 28: / Line 36: @@
 <imgcaption image2|First zone to modify in the INVA.F subroutine>{{ :optim:optim_inva_1.png |}}</imgcaption>
 \\
-In the case shown in <imgref image2> with IDENT=4444, the first curve $REACTION(1)$ corresponds to the compression force on a cylinder. The reaction on DOF 2 (Y-direction) at node 205 is the reaction at the pilot node of the foundation in the axisymetric case; this reaction multiplied by $2\pi$ gives the compression reaction on the cylinder. The second curve, $REACTION(2)$, is the coordinate of DOF 1 (X-direction) of node 3 at the end of the time step.
+In the case shown in <imgref image2> with IDENT=4444, the first curve $REACTION(1)$ corresponds to the compression force on a cylinder. The reaction on DOF 2 (Y-direction) at node 205 is the reaction at the pilot node of the foundation in the axisymmetric case; this reaction multiplied by $2\pi$ gives the compression reaction on the cylinder. The second curve, $REACTION(2)$, is the coordinate of DOF 1 (X-direction) of node 3 at the end of the time step.
 \\ \\
 The second and third zones are used for the implementation of the perturbed curves. The second zone is for the positive perturbation ($REACTION_P$) while the third is for negative perturbation ($REACTION_M$). In these cases, matrices CONEC and SIGVA must be replaced respectively by CONEC_PERT_P or CONEC_PERT_M, and SIGVA_PERT_P or SIGVA_PERT_M.
@@ Line 37: / Line 45: @@
 \\ \\
 <imgcaption image4|Fourth zone of the INVA.F subroutine>{{ :optim:optim_inva_4.png |}}</imgcaption>
+==== Implementation of the printing in WSENSM.F ====
+The results computed in INVA.F at each time step are then sent to the WSENSM.F subroutine to be printed in a *.sm file and in a *.fd file. The *.sm file contains the values of the curves and their derivatives for every time step and is used by Optim to compute the objective function and its derivative. The *.fd file only contains the finite element curves and can be used to easily visualize results in postprocessing. \\
+Similarly to the INVA.F subroutine, users must indicate their IDENT in an "IF" condition. Then, the printing in the *.sm file (ntsm)must be defined as follows:
+  * On the first line, write the abscissa and ordinates (REACTION(1)) of the first curve;
+  * On the second line, write the derivatives of this curve with respect to the parameters;
+  * If there are more than one curve, repeat line 1 and 2 for REACTION(I)
+Afterwards, the curves can be printed in the *.fd file (ntfd)
+__Example:__
+    if(IDENT.EQ.XXXX) then
+        write(ntsm,*) abscissa, reaction(1)
+        write(ntsm,*) DUeF_DX(1,NBPAR_OPTOT)
+        write(ntsm,*) abscissa, reaction(2)
+        write(ntsm,*) DUeF_DX(2,NBPAR_OPTOT)
+        write(ntfd,*) abscissa, reaction(1)
+        write(ntfd,*) abscissa, reaction(2)
+    endif
+\\ The example for IDENT=4444 is illustrated in <imgref image4>, where the abscissa corresponds to the height of the cylinder during the compression loading.
+<imgcaption image5|>{{ :optim:optim_wsensm.png |}}</imgcaption>
+----
+==== Files ====
+To launch a simulation with Lagamine Inverse (even without using Optim), specific files *.op and *.ia are required to define which parameters are optimized. The description of these files can be found [[optim:files|here]].
+----
+===== Optim =====
+To launch an optimization with Optim, several files are required:
+  * Lagamine simulation files *.lag and *ex.dat;
+  * Definition of the optimized parameter initial values *.op;
+  * Definition of the number of curves and parameters to be optimized *.ia;
+  * Definition of the experimental curve(s) *.exp;
+  * Main input for Optim *.info.
+The structure of these files is detailed in the [[optim:files|File]] section of this manual.
+----
+==== Structure of the code ====
+The code Optim is structured in several subroutines:
+  * Main_levenberg: reading of files *.ia, *.op, *.exp and *.info + initialization of variables;
+  * pre_optim: initialization of optimization parameters;
+  * algo_leven: Levenberg-Marquardt algorithm;
+  * fcn: execution of Lagamine Inverse simulation, interpolation of the curves at points i=1,NPOI, computation of fvec vector containing the residuals at each point;
+  * fdjac: interpolation of the derivatives and computation of matrix fdjac containing the derivative of the curves at points i.
+The algorithm can be summed up as follows:
+  * **MAIN_LEVENBERG** \\ Read *.info file, *.exp file, *.op file \\ Run prepro \\ Initialize variables and allocate memory \\ Call PRE_OPTIM
+      * **PRE_OPTIM** \\ Check input parameters \\ Initialize Optim parameters \\ Call ALGO_LEVEN
+          * **ALGO_LEVEN** \\ Check input parameters \\ Call:
+              * **FCN** \\ Launch Lagamine simulation \\ Read *.sm file \\ Compute EF and REF curves
+              * **ENORM** \\ Compute the norm (objective function)
+              * **FDJAC** \\ Compute sensitivity matrix (Jacobian) from *.sm file
+              * **QRFAC** \\ QR factorization of the Jacobian
+              * **LMPAR** \\ Determine Levenberg-Marcquardt parameters
+          * Check for convergence \\ If no -> loop \\ If yes -> end
+----
+==== Files used by Optim ====
+^Type^Unit^Description^
+|.exp|1|Experimental (reference) curve|
+|.info.FPA|2|Recording of every optimization step (parameters + norm)|
+|.fd|8|Result from Lagamine Inverse|
+|NFEV.fd|9|Result from Lagamine Inverse at iteration NFEV|
+|.sm|10|Result from Lagamine Inverse|
+|ex.dat|11|Loading file for Lagamine|
+|FCT_OBJECTIF.OPT|12|Result file|
+|.op|13|Parameters to be optimized|
+|.ia|20|Input data for Lagamine Inverse|
+|.info|78|Input data for the optimization|
+|fvec.vm|88|Record difference between EF curve and REF curve|
+==== Results and output files ====
+During the optimization, the intermediary results are printed out in the console window as well as in the *info.FPA file. \\ When the objective function is reduced, the result and the corresponding parameters are written in the FCT_OBJECTIF.OPT file.

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