updates

include/amscppperm1/amscppperm1.hpp

@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <math.h>
 #include <new>
+#include <initializer_list>
 
 extern "C"
 {
@@ -89,6 +90,7 @@ public:
     ipermutation(const int _length);
     ipermutation(const int _index, const int _length);
     ipermutation(const int *parray, const int _length);
+    ipermutation(std::initializer_list<int> q);
     ~ipermutation();
 
     ipermutation(const ipermutation& other);
@@ -98,6 +100,8 @@ public:
     ipermutation operator=(const ipermutation &other);
     int& operator[](const int ind);
     const int& operator[](const int ind) const;
+    int& at(const int ind);
+    const int& at(const int ind) const;
 
     bool valid() const;
     bool operator==(const ipermutation other) const;
@@ -121,6 +125,8 @@ public:
 
     void print(int style=0);
 
+    void recalc_from_perm();
+
 };
 
 ipermutation ipermutation_first(int _nlength);
@@ -128,18 +134,54 @@ ipermutation ipermutation_last(int _nlength);
 int levi_civita(const ipermutation p);
 
 void test_ipermutation1();
+void test_ipermutation2();
+
+
+
+
 
 // non-indexable permutation class
 // the same permutation logic, but for larger permutation sets
 // can't index, can't increment or decrement a sequence, but can still
 // compose, test validity, test levi_civita sign, apply to arrays, etc.
+//
+//maybe I *can* increment/decrement by converting to a multi-index (later, possibly not essential)
 class permutation
 {
     public:
     int length;
     int *data;
+
+    permutation();
+    permutation(const int _length);
+    permutation(const int *parray, const int _length);
+    permutation(std::initializer_list<int> q);
+    ~permutation();
+
+    permutation(const permutation& other);
+
+    int resize(const int _nlength);
+
+    permutation operator=(const permutation &other);
+
+    bool valid() const;
+    bool operator==(const permutation &other) const;
+
+    int& operator[](const int ind);
+    const int& operator[](const int ind) const;
+    int& at(const int ind);
+    const int& at(const int ind) const;
     
     
+
+    static permutation first(int length);
+    static permutation last(int length);
+
+    permutation operator*(const permutation &other) const; //composition
+    permutation inverse() const;
+
+    int _intl_calculate_mindex(int *mindex, int *wrk);
+    int levi_civita();
 };
 
 

src/amscppperm1/ipermutation.cpp

@@ -0,0 +1,541 @@
+#include <amscppperm1/amscppperm1.hpp>
+
+namespace ams
+{
+namespace perm
+{
+
+    ipermutation::ipermutation()
+    {
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        return;
+    }
+
+    ipermutation::~ipermutation()
+    {
+        if(perm!=NULL) {delete[] perm; perm = NULL;}
+        if(mind!=NULL) {delete[] mind; mind = NULL;}
+        if(wrk!=NULL) {delete[] wrk; wrk = NULL;}
+        length = 0;
+        index = -1;
+
+        return;
+    }
+
+    ipermutation::ipermutation(const int _length)
+    {
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        this->resize(_length);
+    }
+
+    ipermutation::ipermutation(const int _index, const int _length)
+    {
+        int res = perm_failure;
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        if(_length>0)
+        {
+            res = this->resize(_length);
+            if(res==perm_success)
+            {
+                index = _index;
+                amsperm1_index_to_mindex(index,mind,length);
+                amsperm1_mindex_to_perm(mind,perm,wrk,length);
+            }
+        }  
+    }
+
+    ipermutation::ipermutation(const int *parray, const int _length)
+    {
+        int I;
+        int res = perm_failure;
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        if(_length>0)
+        {
+            res = this->resize(_length);
+            if(res==perm_success)
+            {
+                for(I=0;I<length;I++) perm[I] = parray[I];
+                amsperm1_perm_to_mindex(perm,mind,wrk,length);
+                index = amsperm1_mindex_to_index(mind,length);
+            }
+        }  
+        return;
+    }
+
+    ipermutation::ipermutation(std::initializer_list<int> q)
+    {
+        int I;
+        //int elem;
+        int res = perm_failure;
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        if(q.size()>0)
+        {
+            res = this->resize(q.size());
+            if(res==perm_success)
+            {
+                //for(I=0;I<length;I++) perm[I] = q[I];
+                //need to access things with annoying c++ish iterators
+                I = 0;
+                for(int elem : q)
+                {
+                    perm[I] = elem;
+                    if(I<length) I++;
+                }
+                amsperm1_perm_to_mindex(perm,mind,wrk,length);
+                index = amsperm1_mindex_to_index(mind,length);
+            }
+        }
+
+        return;
+    }
+
+    int ipermutation::resize(const int _nlength)
+    {
+        int ret = perm_success;
+
+        int *newperm = NULL;
+        int *newmind = NULL;
+        int *newwrk = NULL;
+        int newind;
+
+        int I;
+
+        if(_nlength<=0)
+        {
+            length = 0;
+            index = -1;
+            if(perm!=NULL) {delete[] perm; perm=NULL;}
+            if(mind!=NULL) {delete[] mind; mind=NULL;}
+            if(wrk!=NULL) {delete[] wrk; wrk=NULL;}
+            
+            return ret;
+        }
+
+        newperm = new(std::nothrow) int[_nlength];
+        newmind = new(std::nothrow) int[_nlength];
+        newwrk = new(std::nothrow) int[_nlength];
+        
+        if(newperm==NULL || newmind == NULL || newwrk == NULL)
+        {
+            if(newperm!=NULL) {delete[] newperm; newperm=NULL;}
+            if(newmind!=NULL) {delete[] newmind; newmind=NULL;}
+            if(newwrk!=NULL) {delete[] newwrk; newwrk=NULL;}
+
+            ret = perm_failure;
+            return ret;
+        }
+
+        for(I=0;I<length && I<_nlength; I++)
+        {
+            newmind[I] = mind[I];
+        }
+        for(I=length;I<_nlength;I++) newmind[I] = 0;
+
+        newind = amsperm1_mindex_to_index(newmind,_nlength);
+        amsperm1_mindex_to_perm(newmind,newperm,newwrk,_nlength);
+
+        if(perm!=NULL) {delete[] perm; perm = NULL;}
+        if(mind!=NULL) {delete[] mind; mind = NULL;}
+        if(wrk!=NULL) {delete[] wrk; wrk = NULL;}
+        length = 0;
+        index = -1;
+
+        length = _nlength;
+        index = newind;
+        perm = newperm;
+        mind = newmind;
+        wrk = newwrk;
+
+
+        return ret;
+    }
+
+    ipermutation::ipermutation(const ipermutation& other)
+    {
+        int res;
+        length = 0;
+        perm = NULL;
+        index = -1;
+        mind = NULL;
+        wrk = NULL;
+
+        int I;
+
+        if(this!=&other)
+        {
+            res = this->resize(other.length);
+            if(res==perm_success)
+            {
+               for(I=0;I<length;I++)
+               {
+                this->perm[I] = other.perm[I];
+                this->wrk[I] = other.wrk[I];
+                this->mind[I] = other.mind[I];
+                this->index = other.index;
+               }  
+            }
+        }
+    }
+
+    ipermutation ipermutation::operator=(const ipermutation &other)
+    {
+        int res;
+        int I;
+        if(this!=&other)
+        {
+            res = this->resize(other.length);
+            if(res==perm_success)
+            {
+               for(I=0;I<length;I++)
+               {
+                this->perm[I] = other.perm[I];
+                this->wrk[I] = other.wrk[I];
+                this->mind[I] = other.mind[I];
+                this->index = other.index;
+               }  
+            }
+        }
+
+        return *this;
+    }
+
+    int& ipermutation::operator[](const int ind)
+    {
+        return perm[ind];
+    }
+
+    const int& ipermutation::operator[](const int ind) const
+    {
+        return perm[ind];
+    }
+
+    int& ipermutation::at(const int ind)
+    {
+        return perm[ind];
+    }
+
+    const int& ipermutation::at(const int ind) const
+    {
+        return perm[ind];
+    }
+
+    int factorial(int n)
+    {
+        return amsperm1_factorial(n);
+    }
+
+    bool ipermutation::valid() const
+    {
+        bool ret = 1;
+        int *lmind = NULL;
+        int *lwrk = NULL;
+        int *lperm = NULL;
+
+        if(index<0 || index>=factorial(length))
+        {
+            ret = 0; return ret;
+        }
+
+        //other tests - skip for speed?
+
+        return ret;
+    }
+
+    bool ipermutation::operator==(const ipermutation other) const
+    {
+        bool ret = 1;
+        int I;
+        
+        if(length!=other.length)
+        {
+            ret = 0; return ret;
+        }
+        if(index != other.index)
+        {
+            ret = 0; return ret;
+        }
+
+        //additional tests (skip for speed?)
+        for(I=0;I<length && I<other.length;I++)
+        {
+            if(perm[I]!=other.perm[I]) {ret = 0; break;}
+            if(mind[I]!=other.mind[I]) {ret = 0; break;}
+        }
+
+        return ret;
+    }
+
+    ipermutation ipermutation_first(int _nlength)
+    {
+        ipermutation ret = ipermutation(0,_nlength);
+        return ret;
+    }
+
+    ipermutation ipermutation_last(int _nlength)
+    {
+        int f = factorial(_nlength);
+        ipermutation ret = ipermutation(f-1,_nlength);
+        return ret;
+    }
+
+    int levi_civita(const ipermutation p)
+    {
+        int ret = 0;
+        bool v = p.valid();
+        if(v)
+        {
+            ret = 2*(!(p.index%2))-1;
+        }
+        return ret;
+    }
+
+    //pre-increment operator
+    ipermutation& ipermutation::operator++()
+    {
+        int I;
+        if(valid())
+        {
+            if(index+1>=0 && index+1<factorial(length))
+            {
+                index = index + 1;
+                amsperm1_index_to_mindex(index,mind,length);
+                amsperm1_mindex_to_perm(mind,perm,wrk,length);
+            } 
+            else
+            {
+                index = -1;
+                for(I=0;I<length;I++)
+                {
+                    perm[I] = -1;
+                    mind[I] = -1;
+                    wrk[I] = 0;
+                }
+            }
+        }
+        return *this;
+    }
+
+    ipermutation& ipermutation::operator--()
+    {
+        int I;
+        if(valid())
+        {
+            if(index-1>=0 && index-1<factorial(length))
+            {
+                index = index - 1;
+                amsperm1_index_to_mindex(index,mind,length);
+                amsperm1_mindex_to_perm(mind,perm,wrk,length);
+            } 
+            else
+            {
+                index = -1;
+                for(I=0;I<length;I++)
+                {
+                    perm[I] = -1;
+                    mind[I] = -1;
+                    wrk[I] = 0;
+                }
+            }
+        }
+        return *this;
+    }
+
+    //post-increment operators
+    ipermutation ipermutation::operator++(int)
+    {
+        ipermutation ret = *this;
+        //++ret;
+        this->operator++();
+        return ret;
+    }
+
+    ipermutation ipermutation::operator--(int)
+    {
+        ipermutation ret = *this;
+        //--ret;
+        this->operator--();
+        return ret;
+    }
+
+    void ipermutation::print(int style)
+    {
+        int I;
+        if(style==0)
+        {
+            printf("{");
+            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
+            printf("%d}",perm[length-1]);
+        }
+        else if(style==1)
+        {
+            printf("%d:{",index);
+            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
+            printf("%d}",perm[length-1]);
+        }
+        else if(style==2)
+        {
+            printf("ipermutation[%d]:{",index);
+            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
+            printf("%d}",perm[length-1]);
+        }
+        return;
+    }
+
+    void test_ipermutation1()
+    {
+        ipermutation a = ipermutation(4);
+        ipermutation *b = NULL;
+
+        b = new(std::nothrow) ipermutation(4);
+
+        a.print(); printf("\n");
+        b->print(); printf("\n");
+        a++;
+        a.print(); printf("\n");
+        ++a; a.print(); printf("\n");
+        a++;
+        a++;
+        a++;
+        *b = a;
+        b->print(2); printf("\n");
+        b->resize(3);
+        a.resize(5);
+        a.print(); printf("\n");
+        b->print(); printf("\n");
+        int I;
+        *b = ipermutation_first(3);
+        for(I=0;I<8;I++)
+        {
+            
+            b->print(2); printf("\n");
+            (*b)++;
+        }
+
+        for(a=ipermutation_last(3);a.valid();a--)
+        {
+            a.print(2); printf("\n");
+        }
+
+        delete(b);
+
+        return;
+    }
+
+    void ipermutation::recalc_from_perm()
+    {
+        amsperm1_perm_to_mindex(perm,mind,wrk,length);
+        index = amsperm1_mindex_to_index(mind,length);
+        return;
+    }
+
+    //compose permutations
+    ipermutation ipermutation::operator*(const ipermutation b) const
+    {
+        int I,J;
+        ipermutation ret = ipermutation(this->length);
+        for(I=0;I<length;I++)
+        {
+            J = this->perm[I];
+            ret[I] = b[J];
+        }
+        ret.recalc_from_perm();
+
+        return ret;
+    }
+    
+    //invert permutation
+    ipermutation ipermutation::inverse() const
+    {
+        int I,J;
+        ipermutation ret = ipermutation(this->length);
+        for(I=0;I<length;I++)
+        {
+            J = this->perm[I];
+            ret[J] = I;
+        }
+
+        ret.recalc_from_perm();
+
+
+        return ret;
+    } 
+
+    //returns first and last permutations of a given lengthension
+    ipermutation ipermutation::first(int _nlength)
+    {
+        ipermutation ret = ipermutation(0,_nlength);
+        return ret;
+    }
+
+    ipermutation ipermutation::last(int _nlength)
+    {
+        int f = factorial(_nlength);
+        ipermutation ret = ipermutation(f-1,_nlength);
+        return ret;
+    }
+
+    int ipermutation::levi_civita() const
+    {
+        int ret = 0;
+        if(valid())
+        {
+            ret = 2*(!(index%2))-1;
+        }
+        return ret;
+    }
+
+    void test_ipermutation2()
+    {
+        ipermutation a,b,c;
+        int q1[] = {2,0,1,3};
+        int q2[] = {3,0,2,1};
+
+        a = ipermutation(q1,4);
+        b = ipermutation({3,0,2,1});
+        c = a*b;
+        a.print(); printf("\n");
+        b.print(); printf("\n");
+        c.print(); printf("\n");
+        c = b*a;
+        c.print(); printf("\n");
+        
+        b = {3,0,2,1};
+        b = a.inverse();
+        c = b*a;
+        
+        a.print(); printf("\n");
+        b.print(); printf("\n");
+        c.print(); printf("\n");
+        c = a*b;
+        c.print(); printf("\n");
+        
+        return;
+    }
+
+}; //end namespace perm
+}; //end namespace ams

src/amscppperm1/permutation.cpp

@@ -5,445 +5,356 @@ namespace ams
 namespace perm
 {
 
-    ipermutation::ipermutation()
-    {
-        length = 0;
-        perm = NULL;
-        index = -1;
-        mind = NULL;
-        wrk = NULL;
-
-        return;
-    }
-
-    ipermutation::~ipermutation()
-    {
-        if(perm!=NULL) {delete[] perm; perm = NULL;}
-        if(mind!=NULL) {delete[] mind; mind = NULL;}
-        if(wrk!=NULL) {delete[] wrk; wrk = NULL;}
-        length = 0;
-        index = -1;
-
-        return;
-    }
+permutation::permutation()
+{
+    length = 0;
+    data = NULL;
+    return;
+}
 
-    ipermutation::ipermutation(const int _length)
-    {
-        length = 0;
-        perm = NULL;
-        index = -1;
-        mind = NULL;
-        wrk = NULL;
+permutation::~permutation()
+{
+    length = 0;
+    if(data!=NULL) {delete[] data; data=NULL;}
+}
 
-        this->resize(_length);
-    }
+permutation::permutation(const permutation& other)
+{
+    int res;
+    int I;
+    length = 0;
+    data = NULL;
 
-    ipermutation::ipermutation(const int _index, const int _length)
+    if(this!=&other)
     {
-        int res = perm_failure;
-        length = 0;
-        perm = NULL;
-        index = -1;
-        mind = NULL;
-        wrk = NULL;
-
-        if(_length>0)
+        res = this->resize(other.length);
+        if(res==perm_success)
         {
-            res = this->resize(_length);
-            if(res==perm_success)
+            for(I=0;I<length&&I<other.length;I++)
             {
-                index = _index;
-                amsperm1_index_to_mindex(index,mind,length);
-                amsperm1_mindex_to_perm(mind,perm,wrk,length);
+                this->data[I] = other.data[I];
             }
-        }  
+        }
     }
+    return;
+}
 
-    ipermutation::ipermutation(const int *parray, const int _length)
-    {
-        int I;
-        int res = perm_failure;
-        length = 0;
-        perm = NULL;
-        index = -1;
-        mind = NULL;
-        wrk = NULL;
+permutation::permutation(const int _length)
+{
+    int res;
+    int I;
+    length = 0;
+    data = NULL;
 
-        if(_length>0)
+    res = this->resize(_length);
+    if(res==perm_success)
+    {
+        for(I=0;I<length;I++)
         {
-            res = this->resize(_length);
-            if(res==perm_success)
-            {
-                for(I=0;I<length;I++) perm[I] = parray[I];
-                amsperm1_perm_to_mindex(perm,mind,wrk,length);
-                index = amsperm1_mindex_to_index(mind,length);
-            }
-        }  
-        return;
+            this->data[I] = I;
+        }
     }
 
-    int ipermutation::resize(const int _nlength)
-    {
-        int ret = perm_success;
-
-        int *newperm = NULL;
-        int *newmind = NULL;
-        int *newwrk = NULL;
-        int newind;
+    return;
+}
 
-        int I;
+permutation::permutation(const int *parray, const int _length)
+{
+    int res;
+    int I;
+    length = 0;
+    data = NULL;
 
-        if(_nlength<=0)
+    res = this->resize(_length);
+    if(res==perm_success)
+    {
+        for(I=0;I<length;I++)
         {
-            length = 0;
-            index = -1;
-            if(perm!=NULL) {delete[] perm; perm=NULL;}
-            if(mind!=NULL) {delete[] mind; mind=NULL;}
-            if(wrk!=NULL) {delete[] wrk; wrk=NULL;}
-            
-            return ret;
+            this->data[I] = parray[I];
         }
+    }
 
-        newperm = new(std::nothrow) int[_nlength];
-        newmind = new(std::nothrow) int[_nlength];
-        newwrk = new(std::nothrow) int[_nlength];
-        
-        if(newperm==NULL || newmind == NULL || newwrk == NULL)
-        {
-            if(newperm!=NULL) {delete[] newperm; newperm=NULL;}
-            if(newmind!=NULL) {delete[] newmind; newmind=NULL;}
-            if(newwrk!=NULL) {delete[] newwrk; newwrk=NULL;}
+    return;
+}
 
-            ret = perm_failure;
-            return ret;
-        }
+permutation::permutation(std::initializer_list<int> q)
+{
+    int res;
+    int I;
+    length = 0;
+    data = NULL;
 
-        for(I=0;I<length && I<_nlength; I++)
+    res = this->resize(q.size());
+    if(res==perm_success)
+    {
+        I = 0;
+        for(int elem : q)
         {
-            newmind[I] = mind[I];
+            data[I] = elem;
+            if(I<length) I++;
         }
-        for(I=length;I<_nlength;I++) newmind[I] = 0;
-
-        newind = amsperm1_mindex_to_index(newmind,_nlength);
-        amsperm1_mindex_to_perm(newmind,newperm,newwrk,_nlength);
-
-        if(perm!=NULL) {delete[] perm; perm = NULL;}
-        if(mind!=NULL) {delete[] mind; mind = NULL;}
-        if(wrk!=NULL) {delete[] wrk; wrk = NULL;}
-        length = 0;
-        index = -1;
+    }
 
-        length = _nlength;
-        index = newind;
-        perm = newperm;
-        mind = newmind;
-        wrk = newwrk;
+    return;
+}
 
 
-        return ret;
-    }
+permutation permutation::operator=(const permutation& other)
+{
+    int res;
+    int I;
 
-    ipermutation::ipermutation(const ipermutation& other)
+    if(this!=&other)
     {
-        int res;
-        length = 0;
-        perm = NULL;
-        index = -1;
-        mind = NULL;
-        wrk = NULL;
-
-        int I;
-
-        if(this!=&other)
+        res = this->resize(other.length);
+        if(res==perm_success)
         {
-            res = this->resize(other.length);
-            if(res==perm_success)
+            for(I=0;I<length&&I<other.length;I++)
             {
-               for(I=0;I<length;I++)
-               {
-                this->perm[I] = other.perm[I];
-                this->wrk[I] = other.wrk[I];
-                this->mind[I] = other.mind[I];
-                this->index = other.index;
-               }  
+                this->data[I] = other.data[I];
             }
         }
     }
+    return *this;
+}
 
-    ipermutation ipermutation::operator=(const ipermutation &other)
-    {
-        int res;
-        int I;
-        if(this!=&other)
-        {
-            res = this->resize(other.length);
-            if(res==perm_success)
-            {
-               for(I=0;I<length;I++)
-               {
-                this->perm[I] = other.perm[I];
-                this->wrk[I] = other.wrk[I];
-                this->mind[I] = other.mind[I];
-                this->index = other.index;
-               }  
-            }
-        }
+int permutation::resize(const int _nlength)
+{
+    int ret = perm_success;
+    int I;
 
-        return *this;
-    }
+    int *newdata = NULL;
 
-    int& ipermutation::operator[](const int ind)
+    if(_nlength<=0)
     {
-        return perm[ind];
+        length = 0;
+        if(data!=NULL) {delete[] data; data=NULL;}
+        ret = perm_failure;
+        return ret;
     }
 
-    const int& ipermutation::operator[](const int ind) const
+    newdata = new(std::nothrow) int[_nlength];
+    if(newdata==NULL)
     {
-        return perm[ind];
+        ret = perm_failure;
+        return ret;
     }
 
-    int factorial(int n)
+    for(I=0;I<length && I<_nlength;I++)
     {
-        return amsperm1_factorial(n);
+        newdata[I] = data[I];
     }
-
-    bool ipermutation::valid() const
+    for(I=length;I<_nlength;I++)
     {
-        bool ret = 1;
-        int *lmind = NULL;
-        int *lwrk = NULL;
-        int *lperm = NULL;
+        newdata[I] = 0; //will have to fill in for it to be a valid permutation
+    }
 
-        if(index<0 || index>=factorial(length))
-        {
-            ret = 0; return ret;
-        }
+    if(data!=NULL) {delete[] data; data=NULL;}
+    data = newdata;
+    length = _nlength;
+    ret = perm_success;
 
-        //other tests - skip for speed?
+    return ret;
+}
 
-        return ret;
+bool permutation::valid() const
+{
+    bool ret = 1;
+    int *wrk = NULL;
+    int I,J;
+
+    wrk = new(std::nothrow) int[length];
+    if(wrk==NULL)
+    {
+        ret = 0; //wrk buffer allocation failed
+        return ret; 
     }
 
-    bool ipermutation::operator==(const ipermutation other) const
+    for(I=0;I<length;I++) wrk[I] = 0;
+
+    for(I=0;I<length;I++)
     {
-        bool ret = 1;
-        int I;
-        
-        if(length!=other.length)
+        J = data[I];
+        if(J<0 || J>=length)
         {
-            ret = 0; return ret;
+            ret = 0;
+            break;
         }
-        if(index != other.index)
+        if(wrk[J]==1)
         {
-            ret = 0; return ret;
+            ret = 0;
+            break;
         }
-
-        //additional tests (skip for speed?)
-        for(I=0;I<length && I<other.length;I++)
+        else
         {
-            if(perm[I]!=other.perm[I]) {ret = 0; break;}
-            if(mind[I]!=other.mind[I]) {ret = 0; break;}
+            wrk[J] = 1;
         }
-
-        return ret;
     }
 
-    ipermutation ipermutation_first(int _nlength)
-    {
-        ipermutation ret = ipermutation(0,_nlength);
-        return ret;
-    }
 
-    ipermutation ipermutation_last(int _nlength)
-    {
-        int f = factorial(_nlength);
-        ipermutation ret = ipermutation(f-1,_nlength);
-        return ret;
-    }
+    if(wrk!=NULL) {delete[] wrk; wrk=NULL;}
+
+    return ret;
+}
 
-    int levi_civita(const ipermutation p)
+bool permutation::operator==(const permutation &other) const
+{
+    int I;
+    bool ret = 1;
+    if(this->length != other.length)
     {
-        int ret = 0;
-        bool v = p.valid();
-        if(v)
-        {
-            ret = 2*(!(p.index%2))-1;
-        }
-        return ret;
+        ret = 0; return ret;
     }
-
-    //pre-increment operator
-    ipermutation& ipermutation::operator++()
+    for(I=0;I<length;I++)
     {
-        int I;
-        if(valid())
+        if(this->data[I]!=other.data[I])
         {
-            if(index+1>=0 && index+1<factorial(length))
-            {
-                index = index + 1;
-                amsperm1_index_to_mindex(index,mind,length);
-                amsperm1_mindex_to_perm(mind,perm,wrk,length);
-            } 
-            else
-            {
-                index = -1;
-                for(I=0;I<length;I++)
-                {
-                    perm[I] = -1;
-                    mind[I] = -1;
-                    wrk[I] = 0;
-                }
-            }
+            ret = 0;
+            break;
         }
-        return *this;
     }
 
-    ipermutation& ipermutation::operator--()
+    return ret;
+}
+
+int permutation::_intl_calculate_mindex(int *mindex, int *wrk)
+{
+    int ret = perm_success;
+    //if(!valid())   //<--- a redundant test given that this is only called from levi_civita
+    //{
+    //    ret = perm_failure;
+    //    return ret;
+    //}
+
+    int I,J,K,L;
+
+    for(I=0;I<length;I++) wrk[I]=0;
+    for(I=0;I<length;I++)
     {
-        int I;
-        if(valid())
+        J = data[I];
+        L = 0;
+        for(K=0;K<=J;K++)
         {
-            if(index-1>=0 && index-1<factorial(length))
+            if(wrk[K]==0)
             {
-                index = index - 1;
-                amsperm1_index_to_mindex(index,mind,length);
-                amsperm1_mindex_to_perm(mind,perm,wrk,length);
-            } 
-            else
-            {
-                index = -1;
-                for(I=0;I<length;I++)
-                {
-                    perm[I] = -1;
-                    mind[I] = -1;
-                    wrk[I] = 0;
-                }
+                L = L + 1;
             }
         }
-        return *this;
+        wrk[J] = 1;
+        mindex[I] = L-1;
     }
+    ret = amsperm1_success;
+
+    return ret;
+}
+
+int permutation::levi_civita()
+{
+    int ret = 0;
+    int *mindex = NULL;
+    int *wrk = NULL;
 
-    //post-increment operators
-    ipermutation ipermutation::operator++(int)
+    int Q;
+
+    if(!valid())
     {
-        ipermutation ret = *this;
-        //++ret;
-        this->operator++();
         return ret;
     }
 
-    ipermutation ipermutation::operator--(int)
+    if(length<=0)
     {
-        ipermutation ret = *this;
-        //--ret;
-        this->operator--();
         return ret;
     }
 
-    void ipermutation::print(int style)
+    mindex = new(std::nothrow) int[length];
+    wrk = new(std::nothrow) int[length];
+
+    this->_intl_calculate_mindex(mindex,wrk);
+
+    if(length==1)
     {
-        int I;
-        if(style==0)
-        {
-            printf("{");
-            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
-            printf("%d}",perm[length-1]);
-        }
-        else if(style==1)
-        {
-            printf("%d:{",index);
-            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
-            printf("%d}",perm[length-1]);
-        }
-        else if(style==2)
-        {
-            printf("ipermutation[%d]:{",index);
-            for(I=0;I<length-1;I++) printf("%d,",perm[I]);
-            printf("%d}",perm[length-1]);
-        }
-        return;
+        ret = 0;
+        return ret;
     }
 
-    void test_ipermutation1()
-    {
-        ipermutation a = ipermutation(4);
-        ipermutation *b = NULL;
-
-        b = new(std::nothrow) ipermutation(4);
-
-        a.print(); printf("\n");
-        b->print(); printf("\n");
-        a++;
-        a.print(); printf("\n");
-        ++a; a.print(); printf("\n");
-        a++;
-        a++;
-        a++;
-        *b = a;
-        b->print(2); printf("\n");
-        b->resize(3);
-        a.resize(5);
-        a.print(); printf("\n");
-        b->print(); printf("\n");
-        int I;
-        *b = ipermutation_first(3);
-        for(I=0;I<8;I++)
-        {
-            
-            b->print(2); printf("\n");
-            (*b)++;
-        }
+    Q = (mindex[0] + mindex[1]*length)%2;
 
-        for(a=ipermutation_last(3);a.valid();a--)
-        {
-            a.print(2); printf("\n");
-        }
+    ret = 2*(!Q)-1;
 
-        delete(b);
 
-        return;
-    }
+    if(mindex!=NULL) {delete[] mindex; mindex=NULL;}
+    if(wrk!=NULL) {delete[] wrk; wrk=NULL;}
 
-    //compose permutations
-    ipermutation ipermutation::operator*(const ipermutation b) const
-    {
-        ipermutation ret = ipermutation(this->length);
+    return ret;
+}
 
-        return ret;
-    }
-    
-    //invert permutation
-    ipermutation ipermutation::inverse() const
+permutation permutation::first(int length)
+{
+    permutation ret = permutation(length);
+    int I;
+    for(I=0;I<ret.length;I++)
     {
-        ipermutation ret = ipermutation(this->length);
-
-        return ret;
-    } 
+        ret.data[I] = I;
+    }
+    return ret;
+}
 
-    //returns first and last permutations of a given lengthension
-    ipermutation ipermutation::first(int _nlength)
+permutation permutation::last(int length)
+{
+    permutation ret = permutation(length);
+    int I;
+    for(I=0;I<ret.length;I++)
     {
-        ipermutation ret = ipermutation(0,_nlength);
-        return ret;
+        ret.data[I] = ret.length-I-1;
     }
+    return ret;
+}
 
-    ipermutation ipermutation::last(int _nlength)
+permutation permutation::operator*(const permutation &other) const
+{
+    int I,J;
+    permutation ret = permutation(this->length);
+    for(I=0;I<length;I++)
     {
-        int f = factorial(_nlength);
-        ipermutation ret = ipermutation(f-1,_nlength);
-        return ret;
+        J = this->data[I];
+        ret[I] = other[J];
     }
 
-    int ipermutation::levi_civita() const
+    return ret;
+}
+
+permutation permutation::inverse() const
+{
+    int I,J;
+    permutation ret = permutation(this->length);
+    for(I=0;I<length;I++)
     {
-        int ret = 0;
-        if(valid())
-        {
-            ret = 2*(!(index%2))-1;
-        }
-        return ret;
+        J = this->data[I];
+        ret[J] = I;
     }
 
+    return ret;
+}
+
+int& permutation::operator[](const int ind)
+{
+    return data[ind];
+}
+
+const int& permutation::operator[](const int ind) const
+{
+    return data[ind];
+}
+
+int& permutation::at(const int ind)
+{
+    return data[ind];
+}
+
+const int& permutation::at(const int ind) const
+{
+    return data[ind];
+}
 
 }; //end namespace perm
 }; //end namespace ams

src/main.cpp

@@ -6,5 +6,6 @@ int main(int argc, char* argv[])
     printf("ams c++ permutation library tests.\n");
     //amsperm1_test_basicperm1();
     //ams::perm::test_ipermutation1();
+    ams::perm::test_ipermutation2();
     return ret;
 }