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Silviu Marian Udrescu 2020-05-10 20:22:43 -04:00 committed by GitHub
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8 changed files with 905 additions and 127 deletions

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#!/bin/csh
# USAGE EXAMPLE: solve_mysteries.scr ops6.txt 2
# USAGE EXAMPLE: solve_mysteries.scr allops.txt 1800
set opsfile = $1
set maxtime = $2
set f = $3
set sigma = $4
set band = $5
set outfile = brute_solutions.dat
set outfile2 = brute_constant.dat
set outfile3 = brute_formulas.dat
if -f $outfile /bin/rm $outfile
if -f $outfile2 /bin/rm $outfile2
if -f $outfile3 /bin/rm $outfile3
echo Trying to solve mysteries with brute force...
echo Trying to solve $f...
echo /bin/cp -p $f mystery.dat
/bin/cp -p $f mystery.dat
echo $opsfile arity2templates.txt mystery.dat results.dat $sigma $band >args.dat
timeout {$maxtime}s ./symbolic_regress_mdl2.x

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#!/bin/csh
# USAGE EXAMPLE: solve_mysteries.scr ops6.txt 2
# USAGE EXAMPLE: solve_mysteries.scr allops.txt 1800
set opsfile = $1
set maxtime = $2
set f = $3
set sigma = $4
set band = $5
set outfile = brute_solutions.dat
set outfile2 = brute_constant.dat
set outfile3 = brute_formulas.dat
if -f $outfile /bin/rm $outfile
if -f $outfile2 /bin/rm $outfile2
if -f $outfile3 /bin/rm $outfile3
echo Trying to solve mysteries with brute force...
echo Trying to solve $f...
echo /bin/cp -p $f mystery.dat
/bin/cp -p $f mystery.dat
echo $opsfile arity2templates.txt mystery.dat results.dat $sigma $band >args.dat
timeout {$maxtime}s ./symbolic_regress_mdl3.x

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@ -11,8 +11,9 @@
! *: multiply
! -: subtract
! /: divide (Put "D" instead of "/" in file, since f77 can't load backslash
!
! Unary:
! O: double (x->2*x); note that this is the letter "O", not zero
! J: double+1 (x->2*x+1)
! >: increment (x -> x+1)
! <: decrement (x -> x-1)
! ~: negate (x-> -x)
@ -25,12 +26,10 @@
! N: arcsin (x->arcsin(x))
! T: arctan (x->arctan(x))
! R: sqrt (x->sqrt(x))
! O: double (x->2*x); note that this is the letter "O", not zero
! J: double+1 (x->2*x+1)
! nonary:
! 0
! 1
! P = pi
! P: pi
! a, b, c, ...: input variables for function (need not be listed in functions.dat)
program symbolic_regress
@ -44,7 +43,7 @@
integer arities(21), nvar, nvarmax, nmax, lnblnk
parameter(nvarmax=20, nmax=10000000)
real*8 f, newloss, minloss, maxloss, rmsloss, xy(nvarmax+1,nmax), epsilon, DL, DL2, DL3
parameter(epsilon=0.000000000000000000001)
parameter(epsilon=0.00000001)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\OJLESCANTR01P"/
integer nn(0:2), ii(nmax), kk(nmax), radix(nmax)
@ -155,116 +154,4 @@
stop
end
real*8 function f(n,arities,ops,x) ! n=number of ops, x=arg vector
implicit none
integer nmax, n, i, j, arities(n), arity, lnblnk
character*60 ops
parameter(nmax=100)
real*8 x(nmax), y, stack(nmax)
character op
!write(*,*) 'Evaluating function with ops = ',ops(1:n)
!write(*,'(3f10.5,99i3)') (x(i),i=1,3), (arities(i),i=1,n)
j = 0 ! Number of numbers on the stack
do i=1,n
arity = arities(i)
op = ops(i:i)
if (arity.eq.0) then ! This is a nonary function
if (op.eq."0") then
y = 0.
else if (op.eq."1") then
y = 1.
else if (op.eq."P") then
y = 4.*atan(1.) ! pi
else
y = x(ichar(op)-96)
end if
else if (arity.eq.1) then ! This is a unary function
if (op.eq.">") then
y = stack(j) + 1
else if (op.eq."<") then
y = stack(j) - 1
else if (op.eq."~") then
y = -stack(j)
else if (op.eq."\") then
y = 1./stack(j)
else if (op.eq."L") then
y = log(stack(j))
else if (op.eq."E") then
y = exp(stack(j))
else if (op.eq."S") then
y = sin(stack(j))
else if (op.eq."C") then
y =cos(stack(j))
else if (op.eq."A") then
y = abs(stack(j))
else if (op.eq."N") then
y = asin(stack(j))
else if (op.eq."T") then
y = atan(stack(j))
else if (op.eq."O") then
y = 2.*stack(j)
else if (op.eq."J") then
y = 1+2.*stack(j)
else
y = sqrt(stack(j))
end if
else ! This is a binary function
if (op.eq."+") then
y = stack(j-1)+stack(j)
else if (op.eq."-") then
y = stack(j-1)-stack(j)
else if (op.eq."*") then
y = stack(j-1)*stack(j)
else
y = stack(j-1)/stack(j)
end if
end if
j = j + 1 - arity
stack(j) = y
! write(*,'(9f10.5)') (stack(k),k=1,j)
end do
if (j.ne.1) stop 'DEATH ERROR: STACK UNBALANCED'
f = stack(1)
!write(*,'(9f10.5)') 666.,x(1),x(2),x(3),f
return
end
subroutine multiloop(n,bases,i,done)
! Handles <n> nested loops with loop variables i(1),...i(n).
! Example: With n=3, bases=2, repeated calls starting with i=(000) will return
! 001, 010, 011, 100, 101, 110, 111, 000 (and done=.true. the last time).
! All it's doing is counting in mixed radix specified by the array <bases>.
implicit none
integer n, bases(n), i(n), k
logical done
done = .false.
k = 1
555 i(k) = i(k) + 1
if (i(k).lt.bases(k)) return
i(k) = 0
k = k + 1
if (k.le.n) goto 555
done = .true.
return
end
subroutine LoadMatrixTranspose(nd,n,mmax,m,A,f)
! Reads the n x m matrix A from the file named f, stored as its transpose
implicit none
integer nd,mmax,n,m,j
real*8 A(nd,mmax)
character*60 f
open(2,file=f,status='old')
m = 0
555 m = m + 1
if (m.gt.mmax) stop 'DEATH ERROR: m>mmax in LoadVectorTranspose'
read(2,*,end=666) (A(j,m),j=1,n)
goto 555
666 close(2)
m = m - 1
print *,m,' rows read from file ',f
return
end
include 'tools.f'

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@ -40,13 +40,13 @@
implicit none
character*60 opsfile, templatefile, mysteryfile, outfile, usedfuncs
character*60 comline, functions, ops, formula
integer arities(19), nvar, nvarmax, nmax, lnblnk
integer arities(21), nvar, nvarmax, nmax, lnblnk
parameter(nvarmax=20, nmax=10000000)
real*8 f, newloss, minloss, maxloss, rmsloss, xy(nvarmax+1,nmax), epsilon
real*8 ymax, prefactor, DL, DL2, DL3, limit
parameter(epsilon=0.000000000000000000001)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\LESCANTR01P"/
parameter(epsilon=0.00001)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\OJLESCANTR01P"/
integer nn(0:2), ii(nmax), kk(nmax), radix(nmax)
integer ndata, i, j, n, jmax
integer*8 nformulas

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@ -40,13 +40,13 @@
implicit none
character*60 opsfile, templatefile, mysteryfile, outfile, usedfuncs
character*60 comline, functions, ops, formula
integer arities(19), nvar, nvarmax, nmax, lnblnk
integer arities(21), nvar, nvarmax, nmax, lnblnk
parameter(nvarmax=20, nmax=10000000)
real*8 f, newloss, minloss, maxloss, rmsloss, xy(nvarmax+1,nmax), epsilon
real*8 ymin, prefactor, DL, DL2, DL3, limit
parameter(epsilon=0.000000000000000000001)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\LESCANTR01P"/
parameter(epsilon=0.00001)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\OJLESCANTR01P"/
integer nn(0:2), ii(nmax), kk(nmax), radix(nmax)
integer ndata, i, j, n, jmin
integer*8 nformulas

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! Max Tegmark 171119, 190128-31, 190506, 200427-29
! Loads templates.csv functions.dat and mystery.dat, returns winners.
! Rejects Pareto-dominated formulas not based on hard sup-norm cut, but using a
! hypothesis-testing framework with a z-score z_n = sqrt(n)*(<b_n>-<b_best>)/sigma_best
! scp -P2222 symbolic_regress.f euler@tor.mit.edu:FEYNMAN
! COMPILATION: a f 'f77 -O3 -o symbolic_regress_mdl2.x symbolic_regress_mdl2.f |& more'
! SAMPLE USAGE: call symbolic_regress_mdl2.x 7ops.txt arity2templates.txt mystery2.dat results.dat 10 0
! call symbolic_regress_mdl2.x 6ops.txt arity2templates.txt mysteryB3.dat results.dat 10 0 (takes a few minutes)
! call symbolic_regress_mdl2.x 14ops.txt arity2templates.txt mystery.dat results.dat 10 0
! call symbolic_regress_mdl2.x 14ops.txt arity2templates.txt mystery.dat results.dat 1000 0 (if skips over correct formula)
! functions.dat contains a single line (say "0>+*-/") with the single-character symbols
! that will be used, drawn from this list:
!
! Binary:
! +: add
! *: multiply
! -: subtract
! /: divide (Put "D" instead of "/" in file, since f77 can't load backslash
!
! Unary:
! >: increment (x -> x+1)
! <: decrement (x -> x-1)
! ~: negate (x-> -x)
! \: invert (x->1/x) (Put "I" instead of "\" in file, since f77 can't load backslash
! L: logaritm: (x-> ln(x)
! E: exponentiate (x->exp(x))
! S: sin: (x->sin(x))
! C: cos: (x->cos(x))
! A: abs: (x->abs(x))
! N: arcsin: (x->arcsin(x))
! T: arctan: (x->arctan(x))
! R: sqrt (x->sqrt(x))
!
! nonary:
! 0
! 1
! P = pi
! a, b, c, ...: input variables for function (need not be listed in functions.dat)
program symbolic_regress
call go
end
subroutine go
implicit none
character*60 opsfile, templatefile, mysteryfile, outfile, usedfuncs
character*60 comline, functions, ops, formula
integer arities(21), nvar, nvarmax, nmax, lnblnk
parameter(nvarmax=20, nmax=5000000)
real*8 f, newloss, minloss, maxloss, rmsloss, limit
real*8 xy0(nvarmax+1,nmax), xy(nvarmax+1,nmax), offset(nmax), offst, bestoffset
real*8 epsilon, DL, nu, z
real*8 lossbits, bitmean, bitsdev, bestbits, bitmargin, sigma, bitexcess, ev
parameter(epsilon=1/2.**30)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\OJLESCANTR01P"/
integer nn(0:2), ii(nmax), kk(nmax), radix(nmax), iarr(nmax)
integer ndata, i, j, jtest, n
integer*8 nformulas, nevals
logical done, rejected
character*60 func(0:2), template
nu = 5.
bitmargin = 0. ! "Thickness" of pareto frontier; default 0
open(2,file='args.dat',status='old',err=666)
read(2,*) opsfile, templatefile, mysteryfile, outfile, nu, bitmargin
write(*,'(1a24,f10.3)') 'Rejection threshold.....',nu
write(*,'(1a24,f10.3)') 'Bit margin..............',bitmargin
comline = 'head -1 '//mysteryfile(1:lnblnk(mysteryfile))//' | wc > qaz.dat'
if (system(comline).ne.0) stop 'DEATH ERROR counting columns'
open(2,file='qaz.dat')
read(2,*) i, nvar
close(2)
nvar = nvar - 1
if (nvar.gt.nvarmax) stop 'DEATH ERROR: TOO MANY VARIABLES'
write(*,'(1a24,i8)') 'Number of variables.....',nvar
open(2,file=opsfile,status='old',err=668)
read(2,*) usedfuncs
close(2)
nn(0)=0
nn(1)=0
nn(2)=0
do i=1,lnblnk(usedfuncs)
if (usedfuncs(i:i).eq.'D') usedfuncs(i:i)='/'
if (usedfuncs(i:i).eq.'I') usedfuncs(i:i)='\'
j = index(functions,usedfuncs(i:i))
if (j.eq.0) then
print *,'DEATH ERROR: Unknown function requested: ',usedfuncs(i:i)
stop
else
nn(arities(j)) = nn(arities(j)) + 1
func(arities(j))(nn(arities(j)):nn(arities(j))) = functions(j:j)
end if
end do
! Add nonary ops to retrieve each of the input variables:
do i=1,nvar
nn(0) = nn(0) + 1
func(0)(nn(0):nn(0)) = char(96+i)
end do
write(*,'(1a24,1a22)') 'Functions used..........',usedfuncs(1:lnblnk(usedfuncs))
do i=0,2
write(*,*) 'Arity ',i,': ',func(i)(1:nn(i))
end do
write(*,'(1a24)') 'Loading mystery data....'
call LoadMatrixTranspose(nvarmax+1,nvar+1,nmax,ndata,xy0,mysteryfile)
write(*,'(1a24,i8)') 'Number of examples......',ndata
write(*,'(1a24)') 'Shuffling mystery data....'
call permutation(ndata,iarr)
do i=1,ndata
do j=1,nvar+1
xy(j,i) = xy0(j,iarr(i))
end do
end do
print *,'Searching for best fit...'
nformulas = 0
nevals = 0
bestbits = 1.e6
sigma = 1.d40 ! So that 1st function gets accepted
template = ''
ops='===================='
open(2,file=templatefile,status='old',err=670)
open(3,file=outfile)
555 read(2,'(1a60)',end=665) template
n = lnblnk(template)
!print *,"template:",template(1:n),"#####"
do i=1,n
ii(i) = ichar(template(i:i))-48
radix(i) = nn(ii(i))
kk(i) = 0
end do
done = .false.
do while ((bestbits.gt.0).and.(.not.done))
nformulas = nformulas + 1
! Analyze structure ii:
do i=1,n
ops(i:i) = func(ii(i))(1+kk(i):1+kk(i))
end do
j = 1
jtest = 2 ! Will test after j=2, 3, 5, 9, 17, ... data points
rejected = .false.
do while ((.not.rejected).and.(j.le.ndata)) ! Keep going as long as you can't reject this formula
nevals = nevals + 1
offst = xy(nvar+1,j) - f(n,ii,ops,xy(1,j))
rejected = (.not.((offst.ge.0).or.(offst.le.0))) ! This was a NaN, so reject the formula :-)
!if (rejected) print *,"NaN!"
if (rejected) exit
rejected = abs(offst).gt.(1./epsilon) ! Otherwise numerical cancellation can masquerade as successss
!if (rejected) print *,"Infinity!"
if (rejected) exit
offset(j) = offst
if (j.ge.jtest) then ! Time for another test
call analyze_offset(j,offset,epsilon,bestoffset,bitmean,bitsdev)
bitexcess = bitmean - bestbits - bitmargin
z = sqrt(1.*j)*bitexcess/sigma ! This sigma is for previous winner, not for this candidate
rejected = (z.gt.nu)
jtest = min(2*jtest-1,ndata)
end if
j = j + 1
end do
if (.not.rejected.and.(bitexcess.lt.0.)) then ! We have a new point on the Pareto frontier
bestbits = min(bitmean,bestbits)
rmsloss = 0.
maxloss = 0.
sigma = 0.
do j=1,ndata
newloss = abs(xy(nvar+1,j) - f(n,ii,ops,xy(1,j)) - bestoffset)
rmsloss = rmsloss + newloss**2
if (maxloss.lt.newloss) maxloss = newloss
end do
rmsloss = sqrt(rmsloss/ndata)
sigma = bitsdev
DL = log(1.*nformulas)/log(2.)
ev = (1.*nevals)/nformulas
write(*,'(2f20.12,x,1a22,1i16,6f19.4)') bitmean, limit(bestoffset), ops(1:n), nformulas, DL, DL+ndata*bitmean, rmsloss, maxloss, bitsdev, ev
write(3,'(2f20.12,x,1a22,1i16,6f19.4)') bitmean, limit(bestoffset), ops(1:n), nformulas, DL, DL+ndata*bitmean, rmsloss, maxloss, bitsdev, ev
flush(3)
end if
call multiloop(n,radix,kk,done)
end do
goto 555
665 close(3)
close(2)
print *,'All done: results in ',outfile
return
666 stop 'DEATH ERROR: missing file args.dat'
668 print *,'DEATH ERROR: missing file ',opsfile(1:lnblnk(opsfile))
stop
670 print *,'DEATH ERROR: missing file ',templatefile(1:lnblnk(templatefile))
stop
end
subroutine analyze_offset(n,offset,epsilon,median,bitmean,bitsdev) ! Check how much an array departs from its median
implicit none
integer n, i
real*8 offset(n), epsilon, bitmean, bitsdev
real*8 median, mymedian, x, bits, sum1, sum2
median = mymedian(n,offset)
sum1 = 0.
sum2 = 0.
do i=1,n
x = abs(offset(i)-median)/epsilon
if (x.gt.1) then
bits = 1.44269504089*log(x) ! = log2(x)
else
bits = 0.
end if
sum1 = sum1 + bits
sum2 = sum2 + bits*bits
end do
bitmean = sum1/n
bitsdev = sqrt(abs(sum2/n-bitmean**2))
return
end
include "tools.f"

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! Max Tegmark 171119, 190128-31, 190506, 200427-29
! Loads templates.csv functions.dat and mystery.dat, returns winners.
! Rejects Pareto-dominated formulas not based on hard sup-norm cut, but using a
! hypothesis-testing framework with a z-score z_n = sqrt(n)*(<b_n>-<b_best>)/sigma_best
! scp -P2222 symbolic_regress.f euler@tor.mit.edu:FEYNMAN
! COMPILATION: a f 'f77 -O3 -o symbolic_regress_mdl3.x symbolic_regress_mdl3.f |& more'
! SAMPLE USAGE: call symbolic_regress_mdl3.x 7ops.txt arity2templates.txt mystery2.dat results.dat 10 0
! call symbolic_regress_mdl3.x 6ops.txt arity2templates.txt mysteryB3.dat results.dat 10 0 (takes a few minutes)
! call symbolic_regress_mdl3.x 14ops.txt arity2templates.txt mystery.dat results.dat 10 0
! call symbolic_regress_mdl3.x 14ops.txt arity2templates.txt mystery.dat results.dat 1000 0 (if skips over correct formula)
! functions.dat contains a single line (say "0>+*-/") with the single-character symbols
! that will be used, drawn from this list:
!
! Binary:
! +: add
! *: multiply
! -: subtract
! /: divide (Put "D" instead of "/" in file, since f77 can't load backslash
!
! Unary:
! >: increment (x -> x+1)
! <: decrement (x -> x-1)
! ~: negate (x-> -x)
! \: invert (x->1/x) (Put "I" instead of "\" in file, since f77 can't load backslash
! L: logaritm: (x-> ln(x)
! E: exponentiate (x->exp(x))
! S: sin: (x->sin(x))
! C: cos: (x->cos(x))
! A: abs: (x->abs(x))
! N: arcsin: (x->arcsin(x))
! T: arctan: (x->arctan(x))
! R: sqrt (x->sqrt(x))
!
! nonary:
! 0
! 1
! P = pi
! a, b, c, ...: input variables for function (need not be listed in functions.dat)
program symbolic_regress
call go
end
subroutine go
implicit none
character*60 opsfile, templatefile, mysteryfile, outfile, usedfuncs
character*60 comline, functions, ops, formula
integer arities(21), nvar, nvarmax, nmax, lnblnk
parameter(nvarmax=20, nmax=5000000)
real*8 f, newloss, minloss, maxloss, rmsloss, limit
real*8 xy0(nvarmax+1,nmax), xy(nvarmax+1,nmax), y(nmax), offset(nmax), offst, bestoffset
real*8 epsilon, DL, nu, z
real*8 lossbits, bitmean, bitsdev, bestbits, bitmargin, sigma, bitexcess, ev
real*8 ymin, ymax
parameter(epsilon=1/2.**30)
data arities /2,2,2,2,1,1,1,1,1,1,1,1,1,1,1,1,1,1,0,0,0/
data functions /"+*-/><~\OJLESCANTR01P"/
integer nn(0:2), ii(nmax), kk(nmax), radix(nmax), iarr(nmax)
integer ndata, i, i1, j, jtest, n
integer*8 nformulas, nevals
logical done, rejected
character*60 func(0:2), template
nu = 5.
bitmargin = 0. ! "Thickness" of pareto frontier; default 0
open(2,file='args.dat',status='old',err=666)
read(2,*) opsfile, templatefile, mysteryfile, outfile, nu, bitmargin
write(*,'(1a24,f10.3)') 'Rejection threshold.....',nu
write(*,'(1a24,f10.3)') 'Bit margin..............',bitmargin
comline = 'head -1 '//mysteryfile(1:lnblnk(mysteryfile))//' | wc > qaz.dat'
if (system(comline).ne.0) stop 'DEATH ERROR counting columns'
open(2,file='qaz.dat')
read(2,*) i, nvar
close(2)
nvar = nvar - 1
if (nvar.gt.nvarmax) stop 'DEATH ERROR: TOO MANY VARIABLES'
write(*,'(1a24,i8)') 'Number of variables.....',nvar
open(2,file=opsfile,status='old',err=668)
read(2,*) usedfuncs
close(2)
nn(0)=0
nn(1)=0
nn(2)=0
do i=1,lnblnk(usedfuncs)
if (usedfuncs(i:i).eq.'D') usedfuncs(i:i)='/'
if (usedfuncs(i:i).eq.'I') usedfuncs(i:i)='\'
j = index(functions,usedfuncs(i:i))
if (j.eq.0) then
print *,'DEATH ERROR: Unknown function requested: ',usedfuncs(i:i)
stop
else
nn(arities(j)) = nn(arities(j)) + 1
func(arities(j))(nn(arities(j)):nn(arities(j))) = functions(j:j)
end if
end do
! Add nonary ops to retrieve each of the input variables:
do i=1,nvar
nn(0) = nn(0) + 1
func(0)(nn(0):nn(0)) = char(96+i)
end do
write(*,'(1a24,1a22)') 'Functions used..........',usedfuncs(1:lnblnk(usedfuncs))
do i=0,2
write(*,*) 'Arity ',i,': ',func(i)(1:nn(i))
end do
write(*,'(1a24)') 'Loading mystery data....'
call LoadMatrixTranspose(nvarmax+1,nvar+1,nmax,ndata,xy0,mysteryfile)
write(*,'(1a24,i8)') 'Number of examples......',ndata
write(*,'(1a24)') 'Removing problematically small data points....'
ymax = 0.
do i=1,ndata
if (ymax.lt.abs(xy0(nvar+1,i))) ymax=abs(xy0(nvar+1,i))
end do
ymin = 0.001*ymax ! Require all data to exceed this
i1 = 0
print *,ymax,ymin
do i=1,ndata
if (abs(xy0(nvar+1,i)).gt.ymin) then ! Keep this data point
i1 = i1 + 1
do j=1,nvar+1
xy0(j,i1) = xy0(j,i1)
end do
end if
end do
write(*,*) ndata-i1," out of ",ndata," data points discarded for being too close to zero"
ndata = i1
write(*,'(1a24)') 'Shuffling mystery data....'
call permutation(ndata,iarr)
do i=1,ndata
do j=1,nvar+1
xy(j,i) = xy0(j,iarr(i))
end do
y(i) = xy(nvar+1,i)
end do
print *,'Searching for best fit...'
nformulas = 0
nevals = 0
bestbits = 1.e6
sigma = 1.d40 ! So that 1st function gets accepted
template = ''
ops='===================='
open(2,file=templatefile,status='old',err=670)
open(3,file=outfile)
555 read(2,'(1a60)',end=665) template
n = lnblnk(template)
!print *,"template:",template(1:n),"#####"
do i=1,n
ii(i) = ichar(template(i:i))-48
radix(i) = nn(ii(i))
kk(i) = 0
end do
done = .false.
do while ((bestbits.gt.0).and.(.not.done))
nformulas = nformulas + 1
! Analyze structure ii:
do i=1,n
ops(i:i) = func(ii(i))(1+kk(i):1+kk(i))
end do
j = 1
jtest = 2 ! Will test after j=2, 3, 5, 9, 17, ... data points
rejected = .false.
do while ((.not.rejected).and.(j.le.ndata)) ! Keep going as long as you can't reject this formula
nevals = nevals + 1
offst = y(j)/f(n,ii,ops,xy(1,j))
rejected = (.not.((offst.ge.0).or.(offst.le.0))) ! This was a NaN, so reject the formula :-)
!if (rejected) print *,"NaN!"
if (rejected) exit
rejected = (abs(offst).lt.epsilon).or.(abs(offst).gt.1./epsilon) ! Otherwise numerical cancellation can masquerade as success
!rejected = abs(log(abs(offst))).gt.(1./epsilon) ! Otherwise numerical cancellation can masquerade as successss
!if (rejected) print *,"Infinity!"
if (rejected) exit
offset(j) = offst
if (j.ge.jtest) then ! Time for another test
call analyze_offset(j,y,offset,epsilon,bestoffset,bitmean,bitsdev)
bitexcess = bitmean - bestbits - bitmargin
z = sqrt(1.*j)*bitexcess/sigma ! This sigma is for previous winner, not for this candidate
rejected = (z.gt.nu)
jtest = min(2*jtest-1,ndata)
end if
j = j + 1
end do
if (.not.rejected.and.(bitexcess.lt.0.)) then ! We have a new point on the Pareto frontier
bestbits = min(bitmean,bestbits)
rmsloss = 0.
maxloss = 0.
sigma = 0.
do j=1,ndata
newloss = abs(y(j) - f(n,ii,ops,xy(1,j))*bestoffset)
rmsloss = rmsloss + newloss**2
if (maxloss.lt.newloss) maxloss = newloss
end do
rmsloss = sqrt(rmsloss/ndata)
sigma = bitsdev
DL = log(1.*nformulas)/log(2.)
ev = (1.*nevals)/nformulas
write(*,'(2f20.12,x,1a22,1i16,6f19.4)') bitmean, limit(bestoffset), ops(1:n), nformulas, DL, DL+ndata*bitmean, rmsloss, maxloss, bitsdev, ev
write(3,'(2f20.12,x,1a22,1i16,6f19.4)') bitmean, limit(bestoffset), ops(1:n), nformulas, DL, DL+ndata*bitmean, rmsloss, maxloss, bitsdev, ev
flush(3)
end if
call multiloop(n,radix,kk,done)
end do
goto 555
665 close(3)
close(2)
print *,'All done: results in ',outfile
return
666 stop 'DEATH ERROR: missing file args.dat'
668 print *,'DEATH ERROR: missing file ',opsfile(1:lnblnk(opsfile))
stop
670 print *,'DEATH ERROR: missing file ',templatefile(1:lnblnk(templatefile))
stop
end
subroutine analyze_offset(n,y,offset,epsilon,median,bitmean,bitsdev) ! Check how much an array departs from its median
implicit none
integer n, i
real*8 y(n), offset(n), epsilon, bitmean, bitsdev
real*8 median, mymedian, x, f, bits, sum1, sum2
median = mymedian(n,offset)
sum1 = 0.
sum2 = 0.
do i=1,n
f = y(i)/offset(i)
x = abs(y(i)-median*f)/epsilon
if (x.gt.1) then
bits = 1.44269504089*log(x) ! = log2(x)
else
bits = 0.
end if
sum1 = sum1 + bits
sum2 = sum2 + bits*bits
!print *,i,y(i),offset(i),abs(y(i)*(offset(i)-median)),x
!read *
end do
bitmean = sum1/n
bitsdev = sqrt(abs(sum2/n-bitmean**2))
return
end
include "tools.f"

380
Code/tools.f Normal file
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@ -0,0 +1,380 @@
! Max Tegmark 171119, 190128-31, 190506, May 2020
! Binary:
! +: add
! *: multiply
! -: subtract
! /: divide (Put "D" instead of "/" in file, since f77 can't load backslash
! Unary:
! >: increment (x -> x+1)
! <: decrement (x -> x-1)
! ~: negate (x-> -x)
! \: invert (x->1/x) (Put "I" instead of "\" in file, since f77 can't load backslash
! L: logaritm (x-> ln(x)
! E: exponentiate (x->exp(x))
! S: sin: (x->sin(x))
! C: cos: (x->cos(x))
! A: abs: (x->abs(x))
! N: arcsin (x->arcsin(x))
! T: arctan (x->arctan(x))
! R: sqrt (x->sqrt(x))
! O: double (x->2*x); note that this is the letter "O", not zero
! J: double+1 (x->2*x+1)
! nonary:
! 0
! 1
! P: pi
real*8 function f(n,arities,ops,x) ! n=number of ops, x=arg vector
implicit none
integer nmax, n, i, j, arities(n), arity, lnblnk
character*60 ops
parameter(nmax=100)
real*8 x(nmax), y, stack(nmax)
character op
!write(*,*) 'Evaluating function with ops = ',ops(1:n)
!write(*,'(3f10.5,99i3)') (x(i),i=1,3), (arities(i),i=1,n)
j = 0 ! Number of numbers on the stack
do i=1,n
arity = arities(i)
op = ops(i:i)
if (arity.eq.0) then ! This is a nonary function
if (op.eq."0") then
y = 0.
else if (op.eq."1") then
y = 1.
else if (op.eq."P") then
y = 4.*atan(1.) ! pi
else
y = x(ichar(op)-96)
end if
else if (arity.eq.1) then ! This is a unary function
if (op.eq.">") then
y = stack(j) + 1
else if (op.eq."<") then
y = stack(j) - 1
else if (op.eq."~") then
y = -stack(j)
else if (op.eq."\") then
y = 1./stack(j)
else if (op.eq."L") then
y = log(stack(j))
else if (op.eq."E") then
y = exp(stack(j))
else if (op.eq."S") then
y = sin(stack(j))
else if (op.eq."C") then
y =cos(stack(j))
else if (op.eq."A") then
y = abs(stack(j))
else if (op.eq."N") then
y = asin(stack(j))
else if (op.eq."T") then
y = atan(stack(j))
else if (op.eq."O") then
y = 2.*stack(j)
else if (op.eq."J") then
y = 1+2.*stack(j)
else
y = sqrt(stack(j))
end if
else ! This is a binary function
if (op.eq."+") then
y = stack(j-1)+stack(j)
else if (op.eq."-") then
y = stack(j-1)-stack(j)
else if (op.eq."*") then
y = stack(j-1)*stack(j)
else
y = stack(j-1)/stack(j)
end if
end if
j = j + 1 - arity
stack(j) = y
! write(*,'(9f10.5)') (stack(k),k=1,j)
end do
if (j.ne.1) stop 'DEATH ERROR: STACK UNBALANCED'
f = stack(1)
!write(*,'(9f10.5)') 666.,x(1),x(2),x(3),f
return
end
subroutine multiloop(n,bases,i,done)
! Handles <n> nested loops with loop variables i(1),...i(n).
! Example: With n=3, bases=2, repeated calls starting with i=(000) will return
! 001, 010, 011, 100, 101, 110, 111, 000 (and done=.true. the last time).
! All it's doing is counting in mixed radix specified by the array <bases>.
implicit none
integer n, bases(n), i(n), k
logical done
done = .false.
k = 1
555 i(k) = i(k) + 1
if (i(k).lt.bases(k)) return
i(k) = 0
k = k + 1
if (k.le.n) goto 555
done = .true.
return
end
real*8 function limit(x)
implicit none
real*8 x, xmax
parameter(xmax=666.)
if (abs(x).lt.xmax) then
limit = x
else
limit = sign(xmax,x)
end if
return
end
subroutine LoadMatrixTranspose(nd,n,mmax,m,A,f)
! Reads the n x m matrix A from the file named f, stored as its transpose
implicit none
integer nd,mmax,n,m,j
real*8 A(nd,mmax)
character*60 f
open(2,file=f,status='old')
m = 0
555 m = m + 1
if (m.gt.mmax) stop 'DEATH ERROR: m>mmax in LoadVectorTranspose'
read(2,*,end=666) (A(j,m),j=1,n)
goto 555
666 close(2)
m = m - 1
print *,m,' rows read from file ',f
return
end
real*8 function mymedian(n,a)
implicit none
integer n,nmax, i
parameter(nmax=10000000)
real*8 a(n), b(nmax)
if (n.gt.nmax) stop 'DEATH ERROR: n>nmax in mymedian'
do i=1,n
b(i) = a(i)
end do
call sort(n,b)
i = nint((n+.5)/2)
if (i.eq.0) i=1
mymedian = b(i)
return
end
subroutine permutation(n,iarr) ! Return a random permutation of the first n integer:
integer iarr(n), idum, nmax, i
parameter(nmax=10000000)
real*8 arr(nmax), brr(nmax), ran1
if (n.gt.nmax) stop "PERMUTATION DEATH ERROR: nmax TOO SMALL"
idum = -666
do i=1,n
arr(i) = ran1(idum)
brr(i) = i
end do
call sort2(n,arr,brr)
do i=1,n
iarr(i) = nint(brr(i))
end do
return
end
SUBROUTINE sort(n,arr) ! Numerical Recipes Quicksort:
INTEGER n,M,NSTACK
REAL*8 arr(n)
PARAMETER (M=7,NSTACK=50)
INTEGER i,ir,j,jstack,k,l,istack(NSTACK)
REAL*8 a,temp
jstack=0
l=1
ir=n
1 if(ir-l.lt.M)then
do 12 j=l+1,ir
a=arr(j)
do 11 i=j-1,1,-1
if(arr(i).le.a)goto 2
arr(i+1)=arr(i)
11 continue
i=0
2 arr(i+1)=a
12 continue
if(jstack.eq.0)return
ir=istack(jstack)
l=istack(jstack-1)
jstack=jstack-2
else
k=(l+ir)/2
temp=arr(k)
arr(k)=arr(l+1)
arr(l+1)=temp
if(arr(l+1).gt.arr(ir))then
temp=arr(l+1)
arr(l+1)=arr(ir)
arr(ir)=temp
endif
if(arr(l).gt.arr(ir))then
temp=arr(l)
arr(l)=arr(ir)
arr(ir)=temp
endif
if(arr(l+1).gt.arr(l))then
temp=arr(l+1)
arr(l+1)=arr(l)
arr(l)=temp
endif
i=l+1
j=ir
a=arr(l)
3 continue
i=i+1
if(arr(i).lt.a)goto 3
4 continue
j=j-1
if(arr(j).gt.a)goto 4
if(j.lt.i)goto 5
temp=arr(i)
arr(i)=arr(j)
arr(j)=temp
goto 3
5 arr(l)=arr(j)
arr(j)=a
jstack=jstack+2
if(jstack.gt.NSTACK) stop 'NSTACK too small in sort'
if(ir-i+1.ge.j-l)then
istack(jstack)=ir
istack(jstack-1)=i
ir=j-1
else
istack(jstack)=j-1
istack(jstack-1)=l
l=i
endif
endif
goto 1
END
SUBROUTINE sort2(n,arr,brr) ! Numerical Recipes Quicksort:
INTEGER n,M,NSTACK
REAL*8 arr(n),brr(n)
PARAMETER (M=7,NSTACK=50)
INTEGER i,ir,j,jstack,k,l,istack(NSTACK)
REAL*8 a,b,temp
jstack=0
l=1
ir=n
1 if(ir-l.lt.M)then
do 12 j=l+1,ir
a=arr(j)
b=brr(j)
do 11 i=j-1,1,-1
if(arr(i).le.a)goto 2
arr(i+1)=arr(i)
brr(i+1)=brr(i)
11 continue
i=0
2 arr(i+1)=a
brr(i+1)=b
12 continue
if(jstack.eq.0)return
ir=istack(jstack)
l=istack(jstack-1)
jstack=jstack-2
else
k=(l+ir)/2
temp=arr(k)
arr(k)=arr(l+1)
arr(l+1)=temp
temp=brr(k)
brr(k)=brr(l+1)
brr(l+1)=temp
if(arr(l+1).gt.arr(ir))then
temp=arr(l+1)
arr(l+1)=arr(ir)
arr(ir)=temp
temp=brr(l+1)
brr(l+1)=brr(ir)
brr(ir)=temp
endif
if(arr(l).gt.arr(ir))then
temp=arr(l)
arr(l)=arr(ir)
arr(ir)=temp
temp=brr(l)
brr(l)=brr(ir)
brr(ir)=temp
endif
if(arr(l+1).gt.arr(l))then
temp=arr(l+1)
arr(l+1)=arr(l)
arr(l)=temp
temp=brr(l+1)
brr(l+1)=brr(l)
brr(l)=temp
endif
i=l+1
j=ir
a=arr(l)
b=brr(l)
3 continue
i=i+1
if(arr(i).lt.a)goto 3
4 continue
j=j-1
if(arr(j).gt.a)goto 4
if(j.lt.i)goto 5
temp=arr(i)
arr(i)=arr(j)
arr(j)=temp
temp=brr(i)
brr(i)=brr(j)
brr(j)=temp
goto 3
5 arr(l)=arr(j)
arr(j)=a
brr(l)=brr(j)
brr(j)=b
jstack=jstack+2
if(jstack.gt.NSTACK)stop 'NSTACK too small in sort2'
if(ir-i+1.ge.j-l)then
istack(jstack)=ir
istack(jstack-1)=i
ir=j-1
else
istack(jstack)=j-1
istack(jstack-1)=l
l=i
endif
endif
goto 1
END
! Numerical Recipes random number generator:
FUNCTION ran1(idum)
INTEGER idum,IA,IM,IQ,IR,NTAB,NDIV
REAL*8 ran1,AM,EPS,RNMX
PARAMETER (IA=16807,IM=2147483647,AM=1./IM,IQ=127773,IR=2836,
*NTAB=32,NDIV=1+(IM-1)/NTAB,EPS=1.2e-7,RNMX=1.-EPS)
INTEGER j,k,iv(NTAB),iy
SAVE iv,iy
DATA iv /NTAB*0/, iy /0/
if (idum.le.0.or.iy.eq.0) then
idum=max(-idum,1)
do 11 j=NTAB+8,1,-1
k=idum/IQ
idum=IA*(idum-k*IQ)-IR*k
if (idum.lt.0) idum=idum+IM
if (j.le.NTAB) iv(j)=idum
11 continue
iy=iv(1)
endif
k=idum/IQ
idum=IA*(idum-k*IQ)-IR*k
if (idum.lt.0) idum=idum+IM
j=1+iy/NDIV
iy=iv(j)
iv(j)=idum
ran1=min(AM*iy,RNMX)
return
END