Example #1
0
    def run(self, lb, ub):
        self.PzSeq = []
        self.PzPrimes = []
        self.nPzPrimes = []
        self.numSeq = []
        self.tpSeq = []
        self.lBound = lb
        self.uBound = ub
        self.size = self.uBound - self.lBound
        for i in range(self.lBound, self.uBound):
            PzTmp = self.Pz(i)
            self.PzSeq.append((fract(PzTmp).limit_denominator(),
                               fract(1 - PzTmp).limit_denominator()))

        for (Pz, nPz) in self.PzSeq:
            if self.verbosity > 0: print '--------------------'
            if self.verbosity > 0: print '{0}, {1}'.format(Pz, nPz)
            # check if numerator prime
            if self.isPrime(Pz.numerator):
                self.PzPrimes.append(Pz.numerator)
                self.numSeq.append(Pz.numerator)
            if self.isPrime(nPz.numerator):
                self.nPzPrimes.append(nPz.numerator)
                self.numSeq.append(nPz.numerator)
            if self.verbosity > 0: print '--------------------'

        self.tpSeq = self.findTwins(self.numSeq)
        print '--------------------'
        print self.numSeq
        print '--------------------'
        return {
            'PzPrimes': self.PzPrimes,
            'nPzPrimes': self.nPzPrimes,
            'numSeq': self.numSeq
        }
Example #2
0
 def _init_base(self):
     self.rows = self.origrows[:]
     for i, row in enumerate(self.rows):
         if not row: continue
         self.rows[i] = row[:]
     self.m = len(self.rows)-1 #excluding objective row
     self.b = [v[0] for v in self.rows if v] #initial b
     nvars = len(self.vars)
     self.base = list(range(nvars-self.m-1, nvars))
     self.base[0] = 0 #reserved for the objective row
     self.cols = nvars #0 for RHS
     for vi in range(nvars-self.m, nvars):
         if self.vars[vi][0]=='@': break
     else: #no artificial variables
         self.rows[0] = self.fobj[:]
         self.phase = 2 
         return
     #with artificial variables
     self.phase = 1
     sigma = [fract(-1) if self.vars[i][0]=='@' else fract(0)
                for i, a in enumerate(self.fobj)]
     for b, row in zip(self.base, self.rows):
         if row is None: continue
         if self.vars[b][0]!='@': continue
         sigma = [c+v for c,v in zip(sigma,row)]
     self.rows[0] = sigma
Example #3
0
 def getX(i, v):
     if i==0: return '(Obj)', self.getObj()
     if i in self.base:
         return v,self.rows[self.base.index(i)][0]
     if i+1 < len(self.vars) and\
        self.vars[i+1][0]=='!' and i+1 in self.base:
             return v,-self.rows[self.base.index(i)][0]
     return v, fract(0)
Example #4
0
 def _best_objective(self):
     best, idx, sigma = fract(-1), 0, self.rows[0]
     for i in range(1, self.cols):
         if sigma[i] <= 0: continue
         imp = self._improvement(i)
         if imp is None: return i #infinity
         if imp <= best: continue #infty can't be converted
         best, idx = imp, i
     return idx #0: reached optimality
Example #5
0
def fractions(s):
    lst = s.split()
    n1 = n2 = x1 = x2 = 0
    y1 = y2 = 1
    if "+" in lst:
        mid = lst.index("+")
        mark = "+"
    else:
        mid = lst.index("-")
        mark = "-"
    for i in range(mid):
        if len(lst[i]) == 1:
            n1 = lst[i]
        else:
            [x1, y1] = lst[i].split('/')
    for i in range(mid, len(lst)):
        if len(lst[i]) == 1:
            n2 = lst[i]
        else:
            [x2, y2] = lst[i].split('/')
    [x1, x2, y1, y2, n1, n2] = list(map(int, [x1, x2, y1, y2, n1, n2]))
    if n1:
        num1 = n1 * y1 + x1
    else:
        num1 = x1
    if n2:
        num2 = n2 * y2 + x2
    else:
        num2 = x2
    if mark == '+':
        result = fract(num1, y1) + fract(num2, y2)
    else:
        result = fract(num1, y1) - fract(num2, y2)
    n = int(result)
    dem = result - n
    if n and not float(dem):
        print('{}'.format(n))
    elif n:
        print('{} {}'.format(n, str(dem)))
    else:
        print('{}'.format(str(dem)))
Example #6
0
    def _pivot_row(self, col):
        '''always use "smallest_index" to break tie.'''
        if self.degenerated:
            rows = self.degenerated
            puts("degenerated rows:"+ repr(rows))
        else: rows = list(range(1,self.m+1))
        rhs = [self.rows[i][0] for i in rows]
        lhs = [self.rows[i][col] for i in rows]
        ratio = [r/l for l,r in zip(lhs,rhs) if l>0]

        if len(ratio) == 0:
            if not self.degenerated: return 0 #infinite solution
            #OK, we found a way out of degeneracy!
            self._restore()
            return self._pivot_row(col)

        mrat = min(ratio) #ratio==0: degenerated!
        nrat = sum(1 for r in ratio if r==mrat)
        needcare = (mrat == 0 and nrat > 1)

        if needcare and self.virtual_perturbation: 
            lmin, idx = max(lhs)+1, 0
            for i, l, r in zip(rows, lhs, rhs):
                if r == 0 and (lmin > l > 0):
                    lmin, idx = l, i
            return idx #which has lmin, to break cycle
        
        if needcare and self.flat_wolf:
            if not self.degenerated:
                self.vobj = self.rows[0][0] #remember objective value
                self.degenerated = [i for i in rows if self.rows[i][0]==0]
            for i in self.degenerated:
                if self.rows[i][0]: continue #re-randomize?
                #wolf randomization, without recursion (flat)
                self.rows[i][0] = fract(1)/randint(2,10)
            return self._pivot_row(col)

        smallest, ri = len(self.vars) + 1, -1
        for i, l, r in zip(rows, lhs, rhs): #min ratio
            if l <= 0: continue
            if r == mrat * l: #fractions
                if self.base[i] < smallest:
                   smallest, ri = self.base[i], i #smallest_index
        assert ri >= 0, "row index should never be negative!"
        return ri #smallest_index
Example #7
0
from fractions import Fraction as fract
x = set()
for i in range(100,1,-1):
    for z in range(i-1,0, -1):
        if z/i in x:
            z-=1
        else:
            x.add(z/i)
            print(fract(z,i))
print(len(x))#1 to 8 should give len 21
Example #8
0
from fractions import Fraction as fract
x = set()
for i in range(1, 80001):
    for z in range(int((fract(3, 7) * i) - 1 / i), i):
        if z / i >= 3 / 7:
            i += 1
        else:
            print(fract(z, i))
            x.add(fract(z, i))

x = sorted(x)
print('---', x.pop(), '---')
Example #9
0
 def _largest_sigma(self):
     best, idx, sigma = fract(0), 0, self.rows[0]
     for i in range(1, self.cols):
         if sigma[i] <= best: continue
         best, idx = sigma[i], i
     return idx #0: reached optimality
Example #10
0
 def terms(td):
     ts = {}
     for v,c in td.items(): ts[v] = fract(c)
     return ts
Example #11
0
    def __init__(self, prob, interactive=True):
        '''no variable name should start with '@' in prob.'''
        self.text = str(prob)
        self.vars = [''] #reserved
        def terms(td):
            ts = {}
            for v,c in td.items(): ts[v] = fract(c)
            return ts
        sts = [(terms(t),r, fract(b)) for t,r,b,p in prob.sts]
        self.rownames = [p for t,r,b,p in prob.sts]
        for i, (t,r,b) in enumerate(sts):
            if i==0: self.obj_dir = r
            if i==0 and r<0 or i and b < 0: #minimize or b<0
                for v in t: t[v] = -t[v]
                sts[i] = t, -r, -b
            for v in prob.fvs: #free vars
                if v not in t: continue
                t['!%s'%v] = - t[v] #negate coefficient
            for v in t:
                if v not in self.vars:
                    self.vars.append(v)
                    
        self.vars = prob.sortvars(self.vars) #sort by var name
        self.vars[0] = '(RHS)'
        
        #add surplus vars
        for idx, (t,r,b) in enumerate(sts):
            if r>=0: continue
            v = '#%i'%idx
            t[v] = -1
            self.vars.append(v)
        #add slack vars
        for idx, (t,r,b) in enumerate(sts):
            if idx==0 or r<=0: continue
            v = '$%i'%idx #slack
            t[v] = 1
            self.vars.append(v)
        #add artificial vars, in the end.
        #NOTE: not matrix I
        for idx, (t,r,b) in enumerate(sts):
            if idx==0 or r>0: continue
            v = '@%i'%idx #artificial
            t[v] = 1
            self.vars.append(v)
        #ready for tableau
        fobj = sts[0][0]
        self.fobj = [fobj.get(v,0) for v in self.vars]
        self.origrows = [None]
        for i, (t,r,b) in enumerate(sts):
            if i==0: continue #ignore objective
            row = [t.get(v,0) for v in self.vars]
            row[0] = b
            self.origrows.append(row)

        self._method = Tableau._largest_sigma
        self.interactive = interactive
        #The virtual perturbation is not proven
        self.virtual_perturbation = False
        #we may also use flat wolf randomization
        self.flat_wolf = not interactive
        #degenerated rows for wolf randomization
        self.degenerated = ()        
        self.hist = [] #history, to undo