Memory-usage-of-st-wslda.md

 # Arythemtics
 Static codes support two types arithmetics:
-* `double complex`:  `ESIZE=16B`  
+* `double complex`:  `ELEMENT_SIZE=16B`  
 default mode: matrix elements of hamiltonian are assumed to be of complex numbers.  
-* `double`:  `ESIZE=8B`  
+* `double`:  `ELEMENT_SIZE=8B`  
 if you know that matrix elements, as well as the solution, will be real numbers (for examples based on symmetries of your problem) you can speed-up the calculation process by switching to double arythmetics. To do this you need to activate in [predefines.h](https://gitlab.fizyka.pw.edu.pl/gabrielw/wslda/-/blob/public/st-project-template/predefines.h) flag:
 ```c
 /**
@@ -14,5 +14,37 @@ if you know that matrix elements, as well as the solution, will be real numbers
 
 
 # st-wslda-3d
-3D version of the code diagonalized matrix of size: `matrix_size = NX*NY*NZ*2`.  
-Memory needed TODO
+3D version of the code diagonalizes matrix of size:  
+`MATRIX_DIM = NX*NY*NZ*2`.  
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+Memory needed store this matrix in memory is  
+`MATRIX_SIZE = MATRIX_DIM*ELEMENT_SIZE`.  
+To execute diagonalization routine `st-wslda-3d` code needs at most:  
+`REQUIRED_MEMORY < 4*MATRIX_SIZE`,  
+Factor 4 accounts for storage for matrix, storage for eigen-vectors, working space which depends on selected [diagonalization engine](Setting up diagonalization engine) and execution parameters. 
+
+# st-wslda-2d
+In (quasi) 2D formulation of the problem diagonalization of full hamiltonian matrix factorizes into a series of `max(NZ/2,1)` diagonalizations of matrices of size (`NZ/2` arises from fact that there is the degeneracy of states with respect to sign of $`k_z`$ wave-vectors):  
+`MATRIX_DIM = NX*NY*2`  
+and the corresponding matrix size is  
+`MATRIX_SIZE = MATRIX_DIM*ELEMENT_SIZE`.  
+Number of matrices diagonalized  simultaneously is:  
+`NUMBER_OF_SIMULTANUES_DIAGONALIZATIONS = np / (p*q)`  
+where `np` is number of MPI processes  (provided to mpi execution command) and `p` and `q` are input file parameters. 
+To execute diagonalization routine `st-wslda-2d` code needs at most:  
+`REQUIRED_MEMORY < 4*MATRIX_SIZE*NUMBER_OF_SIMULTANUES_DIAGONALIZATIONS`.  
+
+*Note*: if `p` and `q` are not specified in the input file, by default `st-wslda-2d` will select the values that provide the highest parallelization (maximization of a number of simultaneous diagonalization). It means the highest memory request. 
+
+
+# st-wslda-1d
+In (quasi) 1D formulation of the problem diagonalization of full hamiltonian matrix factorizes into a series of `max(NY*NZ/4,1)` diagonalizations of matrices of size:  
+`MATRIX_DIM = NX*2`  
+and the corresponding matrix size is  
+`MATRIX_SIZE = MATRIX_DIM*ELEMENT_SIZE`.  
+Number of matrices diagonalized  simultaneously is:  
+`NUMBER_OF_SIMULTANUES_DIAGONALIZATIONS = np / (p*q)`  
+where `np` is number of MPI processes  (provided to mpi execution command) and `p` and `q` are input file parameters. 
+To execute diagonalization routine `st-wslda-1d` code needs at most:  
+`REQUIRED_MEMORY < 4*MATRIX_SIZE*NUMBER_OF_SIMULTANUES_DIAGONALIZATIONS`.  
+
+*Note*: if `p` and `q` are not specified in the input file, by default `st-wslda-1d` will select the values that provide the highest parallelization (maximization of a number of simultaneous diagonalization). It means the highest memory request. 
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