1 | ! **************************************************************
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2 | !
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3 | ! This file contains the subroutines: mulcan_sim,muca_weight2
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4 | !
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5 | ! Copyright 2003-2005 Frank Eisenmenger, U.H.E. Hansmann,
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6 | ! Shura Hayryan, Chin-Ku
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7 | ! Copyright 2007 Frank Eisenmenger, U.H.E. Hansmann,
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8 | ! Jan H. Meinke, Sandipan Mohanty
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9 | !
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10 | ! **************************************************************
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11 |
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12 | subroutine mulcan_sim
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13 | !
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14 | ! PURPOSE: PERFORM A MULTICANONICAL SIMULATION
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15 | ! REQUIRES AS INPUT THE MULTICANONICAL PARAMETER AS CALCULATED
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16 | ! BY THE SUBROUTINE mulcan_par
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17 | !
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18 | ! CALLS: addang, contacts,energy,metropolis
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19 | !
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20 | include 'INCL.H'
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21 |
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22 | ! external rand
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23 | external muca_weight2
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24 |
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25 | logical restart
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26 |
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27 | parameter(restart=.false.)
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28 | parameter(kmin=-12,kmax=20,ebin=1.0d0)
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29 | parameter(nsweep=100000,nequi=100)
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30 | Parameter(nsave=1000,nmes=10)
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31 | !
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32 | ! restart: .true. = restart of simulation
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33 | ! .false. = start of simulation with random configuration
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34 | ! kmin,kmax: Range of multicanonical parameter
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35 | ! ebin: bin size for multicanonical parameter
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36 | ! nequi: Number of sweeps for equilibrisation
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37 | ! nsweep: Number of sweeps for simulation run
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38 | ! nsave: Number of sweeps after which actual configuration is saved
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39 | ! for re-starts
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40 | ! nmes: Number of sweeps between measurments
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41 | !
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42 |
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43 | dimension xhist(kmin:kmax),ihist(kmin:kmax)
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44 | common/muca2/b(kmin:kmax),alpha(kmin:kmax)
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45 |
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46 |
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47 | ! FILE with last conformation (for re-starts)
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48 | open(8,file='EXAMPLES/start.d')
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49 | ! File with contact map of reference configuration
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50 | open(9,file='EXAMPLES/enkefa.ref')
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51 | ! File with multicanonical parameter
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52 | open(10,file='EXAMPLES/muca.d')
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53 | ! Result file: Time series of certain quantities
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54 | open(11, file='EXAMPLES/time.d')
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55 |
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56 |
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57 | do j=kmin,kmax
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58 | ihist(j)= 0
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59 | end do
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60 |
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61 | nresi=irsml2(1)-irsml1(1) + 1
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62 | ! nresi: Number of residues
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63 |
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64 | ! READ REFERENCE CONTACT MAP
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65 | nci = 0
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66 | do i=1,nresi
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67 | read(9,*) (iref(i,j) , j=1,nresi)
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68 | end do
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69 | do i=1,nresi
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70 | do j=nresi,i+3,-1
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71 | if(iref(i,j).eq.1) nci = nci + 1
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72 | end do
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73 | end do
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74 | write(*,*) 'Number of contacts in reference conformation:',nci
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75 |
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76 | ! READ IN FIELDS WITH MULTICANONICAL PARAMETER
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77 | Do j=kmin,kmax
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78 | read(10,*) i,b(i),alpha(i)
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79 | end do
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80 | !
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81 |
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82 | if(restart) then
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83 | read(8,*) nswm, eol_old
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84 | read(8,*) (xhist(j), j=kmin,kmax)
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85 | do i=1,nvr
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86 | read(8,*) j, x
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87 | iv = idvr(j)
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88 | vlvr(iv) = x
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89 | end do
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90 | write(*,*) 'Last iteration, energy:',nswm,eol_old
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91 | else
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92 | ! _________________________________ random start
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93 | do i=1,nvr
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94 | iv=idvr(i) ! provides index of non-fixed variable
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95 | dv=axvr(iv)*(grnd()-0.5)
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96 | vr=addang(pi,dv)
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97 | vlvr(iv)=vr
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98 | enddo
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99 | end if
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100 | !
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101 | eol = energy()
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102 | write (*,'(e12.5,/)') eol
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103 | call contacts(nhy,nhx,dham)
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104 | write(*,*) 'Number of contacts in start configuration:',nhy
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105 | write(*,*) 'Number of native contacts in start configuration:',
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106 | & nhx
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107 | do i=1,nresi
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108 | write(*,'(62I1)') (ijcont(i,j), j=1,nresi)
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109 | end do
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110 | write(*,*)
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111 | !
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112 |
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113 |
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114 | if(.not.restart) then
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115 | ! =====================Equilibrization by Metropolis
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116 | do nsw=1,nequi
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117 | call metropolis(eol,acz,muca_weight2)
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118 | end do
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119 | do i=kmin,kmax
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120 | ihist(i) = 0
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121 | end do
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122 | nswm = 1
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123 | end if
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124 |
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125 | !======================Simulation
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126 | acz = 0.0d0
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127 | ! LOOP OVER SWEEPS
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128 | do nsw=nswm,nsweep
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129 | !
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130 | ! METROPOLIS UPDATE
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131 | call metropolis(eol,acz,muca_weight2)
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132 | muold = min(kmax,max(kmin,int(eol/ebin+sign(0.5d0,eol))))
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133 | ihist(muold) = ihist(muold) + 1
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134 | !
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135 | ! SAVE ACTUAL CONFORMATIONS FOR RE-STARTS:
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136 | if(mod(nsw,nsave).eq.0) then
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137 | rewind 8
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138 | write(8,*) nswm, eol
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139 | write(8,*) (xhist(j), j=kmin,kmax)
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140 | do i=1,nvr
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141 | iv = idvr(i)
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142 | write(8,*) i,vlvr(iv)
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143 | end do
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144 | end if
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145 | ! Measurements after NMES sweeps
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146 | if(mod(nsw,nmes).eq.0) then
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147 | ! Take a histogram of energy
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148 | do i=kmin,kmax
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149 | xhist(i) = xhist(i) + ihist(i)
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150 | ihist(i) = 0
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151 | end do
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152 | ! Calculate contacts in actual configuartion and compare with reference
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153 | ! configuration
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154 | ! call contacts(nhx,nhy,dham)
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155 | ! nhx : Number of contcats in actual conformation
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156 | ! nhy : Number of contacts which are identical in actual and reference
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157 | ! configuration
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158 | ! dham: Hamming distance between actual and reference configuration
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159 | !
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160 | write(11,'(i7,f12.2,2i8,f12.4)') nsw,eol,nhx,nhy,dham
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161 | end if
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162 | end do
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163 | ! END OF SIMULATION
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164 |
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165 | ! FINAL OUTPUT:
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166 | acz = acz/dble(nsw*nvr)
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167 | write(*,*) 'last energy',eol
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168 | write(*,*) 'aczeptance rate:',acz
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169 |
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170 | ! WRITE DOWN (UN-REWEIGHTED) HISTOGRAM OF MULTICANONICAL SIMULATION
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171 | do i=kmin,kmax
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172 | if(xhist(i).gt.0.0d0) then
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173 | write(*,*) i,xhist(i)
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174 | end if
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175 | end do
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176 | ! =====================
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177 | close(8)
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178 | close(9)
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179 | close(10)
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180 | close(11)
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181 |
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182 | return
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183 | end
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184 |
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185 | ! ************************************************************
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186 | real*8 function muca_weight2(x)
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187 |
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188 | implicit real*8 (a-h,o-z)
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189 | implicit integer*4 (i-n)
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190 |
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191 | Parameter(kmin=-12,kmax=20,ebin=1.0d0)
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192 |
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193 | common/muca2/b(kmin:kmax),alpha(kmin:kmax)
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194 |
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195 | muold = min(kmax,max(kmin,int(x/ebin+sign(0.5d0,x))))
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196 | muca_weight2 = b(muold)*x + alpha(muold)
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197 |
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198 | return
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199 |
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200 | end
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201 |
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202 |
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