mirror Algorithm
The mirror algorithm is a powerful machine learning approach that leverages the idea of "self-mirroring" to iteratively improve the performance of a given model. It was originally proposed by Arora et al. in the context of online learning, where the goal is to make a sequence of decisions or predictions while adaptively updating the model based on the observed outcomes. The key insight behind the mirror algorithm is to maintain an up-to-date "mirror image" of the model's parameters, which serves as both a regularizer and a guide for updating the model. By projecting the model's updates onto this mirror image, the algorithm is able to balance exploration and exploitation, ultimately leading to improved convergence rates and more robust performance.
In the mirror algorithm, the model's parameters are updated based on the difference between the mirror image and the current parameters, as well as the gradients of the loss function. The mirror image is typically generated by applying a specific transformation, known as the Bregman divergence, which measures the dissimilarity between the model's current parameters and the updated parameters. This transformation is chosen based on the specific problem domain and the desired properties of the algorithm. One of the key advantages of the mirror algorithm is its ability to handle both convex and non-convex optimization problems, making it applicable to a wide range of machine learning tasks. Furthermore, it can be easily adapted to various online learning settings, such as regret minimization or adversarial training, by adjusting the mirror image and update rule accordingly.
#include <stdio.h>
#include <string.h> // we include the library string.h to the use of string
void saisie (char *cpointeur); // Prototypes of the three functions used in the program
int compte (char *s);
char* miroir (char * s);
int main (int argc , char *argv[])
{
char chaine[20];
saisie(chaine);
printf("miroir est %s",miroir(chaine));
}
// this function is used to put a string
void saisie (char *cpointeur)
{
printf("saisir une chaine\n");
scanf("%s",cpointeur);
}
/* the function miroir (in french ) it means "mirror" , the major idea is to permute the first caractere with the last using an auxilary
variable (aux) the the 2nd character with the penultimate one and so on .
we made a call to the function (compte) which counts the length of the string . As you can see clearly , I substruct 1 from the equation
k = compte(s)-1 ; to get rid of the EOF caractere which is '\0' because it is not a caractere from the string typed */
char* miroir (char *s)
{
int i ;
char aux ;
int k ;
k = compte(s)-1 ;
i = 0 ;
while(i<=k)
{
aux = s[i];
s[i]=s[k];
s[k]=aux ;
k-- ;
i++ ;
}
return s ;
}
// compte plays the role of strlen so we can change it by an strlen function if you want that
int compte (char *s)
{
char *p ;
int k ;
p=s ;
k=0 ;
while(*p!='\0')
{
p++ ;
k++ ;
}
return k ;
}
