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#!/usr/bin/env python
## Copyright 2015-2022 Ian Jauslin
##
## Licensed under the Apache License, Version 2.0 (the "License");
## you may not use this file except in compliance with the License.
## You may obtain a copy of the License at
##
## http://www.apache.org/licenses/LICENSE-2.0
##
## Unless required by applicable law or agreed to in writing, software
## distributed under the License is distributed on an "AS IS" BASIS,
## WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
## See the License for the specific language governing permissions and
## limitations under the License.
##########################################################################
## ##
## convert flow equations to various formats ##
## ##
##########################################################################
import sys
import re
def print_usage():
print("\nusage:",file=sys.stderr)
print(" export_flow_equation [-i infile] <format> [options]",file=sys.stderr)
print("\nwhere <format> [options] is one of",file=sys.stderr)
print(" C [-l oldl_symbol] [-L newl_symbol] [-C Constant_symbol] [-S]",file=sys.stderr)
print(" javascript [-l oldl_symbol] [-L newl_symbol] [-C Constant_symbol]",file=sys.stderr)
print(" LaTeX [-l oldl_symbol] [-L newl_symbol] [-C Constant_symbol] [-s]",file=sys.stderr)
print("",file=sys.stderr)
# to C
def C_engine(argv,text):
argc=len(argv)
i=1
# defaults
lsym="l"
Lsym="newL"
Csym="C"
oneline=0
while (i<argc):
# arguments requiring a variable
if (argv[i] in ["-l","-L","-C"]):
if(i>=argc-1):
print("error: '"+argv[i]+"' must be followed by a string",file=sys.stderr)
exit(-1)
# symbol for l
if (argv[i]=="-l"):
lsym=argv[i+1]
i=i+2
# symbol for new l
elif (argv[i]=="-L"):
Lsym=argv[i+1]
i=i+2
# symbol for C
elif (argv[i]=="-C"):
Csym=argv[i+1]
i=i+2
# write each equation on a single line
elif (argv[i]=="-S"):
oneline=1
i=i+1
return(convert_C(text,lsym,Lsym,Csym,oneline))
# to LaTeX
def latex_engine(argv,text):
argc=len(argv)
i=1
# defaults
lsym=r'\\ell'
Lsym=r'\\ell'
Csym="C"
oneline=1
while (i<argc):
# arguments requiring a variable
if (argv[i] in ["-l","-L","-C"]):
if(i>=argc-1):
print("error: '"+argv[i]+"' must be followed by a string",file=sys.stderr)
exit(-1)
# symbol for l
if (argv[i]=="-l"):
lsym=argv[i+1]
i=i+2
# symbol for new l
elif (argv[i]=="-L"):
Lsym=argv[i+1]
i=i+2
# symbol for C
elif (argv[i]=="-C"):
Csym=argv[i+1]
i=i+2
# break lines in equation
elif (argv[i]=="-s"):
oneline=0
i=i+1
return(convert_latex(text,lsym,Lsym,Csym,oneline))
# convert to C format
def convert_C(text, lsym, Lsym, Csym, oneline):
# make sure quotients are floats
text=re.sub(r'([0-9])/',r'\1./',text)
# remove newlines
if (oneline==0):
text=text.replace('\n','\\\n')
# end of lines
text=text.replace(',\\',';')
else:
text=text.replace('\n','')
# end of lines
text=text.replace(',',';\n')
# remove extra space
text=re.sub(r' {2,}',' ',text)
# replace left hand side variables
text=re.sub(r'\[(d*)C *([0-9]*)\] =',r'\1'+Csym+r'\2 =', text)
text=re.sub(r'\[(d*)% *([0-9]*)\] =',r'\1'+Lsym+r'[\2] =', text)
# replace right hand side variables
text=re.sub(r'\[(d*)% *([0-9]*)\]',r'*\1'+lsym+r'[\2]',text)
text=re.sub(r'\[(d*)C *([0-9]*)\]',r'*\1'+Csym+r'[\2]',text)
# replace constants in right hand side (and expand powers as products)
match=re.search(r'\[/C([0-9]*)\^([0-9]*)\]',text)
while(match):
power=int(match.group(2))
# product of constants
prod=''
for i in range(power):
prod=prod+'/'+Csym+match.group(1)
text=text.replace('[/C'+match.group(1)+'^'+match.group(2)+']',prod)
match=re.search(r'\[/C([0-9]*)\^([0-9]*)\]',text)
# replace square roots
text=re.sub(r's\{([0-9]*)\}',r'sqrt(\1)',text)
text=text.replace(')sqrt',')*sqrt')
# re-number variables in a sequential fashion
variables=[]
for match in re.finditer(r'\[([0-9]*)\]',text):
index=int(match.group(1))
if index not in variables:
variables.append(index)
variables.sort()
for index in range(len(variables)):
text=text.replace('['+str(variables[index])+']','[new'+str(index)+']')
text=text.replace('[new','[')
return(text+';')
# convert to LaTeX format
def convert_latex(text, lsym, Lsym, Csym, oneline):
# remove newlines
if (oneline==0):
text=text.replace('\n','\\\\\n')
else:
# end of lines
text=text.replace(',',',\\\\')
# remove extra space
text=re.sub(r' {2,}',' ',text)
# remove unnecessary 1's
text=re.sub(r'\(-1\)\[',r'-[',text)
text=re.sub(r'\(1\)\[',r'[',text)
# replace left hand side variables
text=re.sub(r'\[(d*)C *([0-9]*)\] =',r'@\1'+Csym+r'_{\2} =', text)
text=re.sub(r'\[(d*)% *([0-9]*)\] =',r'@\1'+Lsym+r'_{\2} =', text)
# replace right hand side variables
text=re.sub(r'\[(d*)% *([0-9]*)\]',r'@\1'+lsym+r'_{\2}',text)
text=re.sub(r'\[(d*)C *([0-9]*)\]',r'@\1'+Csym+r'_{\2}',text)
# rewrite derivatives
# find the highest order of derivatives
i=0
dstr="d"
index=0
while (index>=0):
index=text.find(r'@'+dstr,index)
i=i+1
dstr=dstr+"d"
#replace derivatives
for j in range(i):
# number of derivs
nrd=i-1-j
dstr=""
for k in range(nrd):
dstr=dstr+"d"
if (nrd>1):
text=text.replace(r'@'+dstr,"\\partial^{"+str(nrd)+"}")
elif (nrd==1):
text=text.replace(r'@'+dstr,"\\partial ")
else:
text=text.replace(r'@'+dstr,"")
# replace constants in right hand side
text=re.sub(r'\[/C([0-9]*)\^([0-9]*)\]',r'\\frac1{'+Csym+r'_{\1}^{\2}}',text)
# remove "^{1}"
text=text.replace("^{1}","")
# replace square roots
text=text.replace('s{','\\sqrt{')
# fractions
text=re.sub(r'\((-?)([0-9]*)/([0-9]*)\)',r'\1\\frac{\2}{\3}',text)
# numbers
#text=re.sub(r'\(([-0-9]*)\)',r'\1',text)
# fix signs
text=re.sub(r'\+-',r'-',text)
return(text)
# read arguments
argc=len(sys.argv)
if (argc<=1):
print_usage()
exit(-1)
i=1
infile=""
while i<argc:
if (sys.argv[i]=="-i"):
if(i<argc-1):
infile=sys.argv[i+1]
i=i+2
else:
print("error: '"+sys.argv[i]+"' must be followed by a filename",file=sys.stderr)
exit(-1)
else:
# read input
if (infile==""):
# read input from stdin
text=sys.stdin.read()
else:
f=open(infile,'r')
text=f.read()
f.close()
if (sys.argv[i]=="C"):
print(C_engine(sys.argv[i:],text))
elif (sys.argv[i]=="javascript"):
# reuse C engine but ensure that the single line option is used
print(C_engine(sys.argv[i:]+["-S"],text))
elif (sys.argv[i]=="LaTeX"):
print(latex_engine(sys.argv[i:],text))
else:
print("error: '"+sys.argv[i]+"' is not supported",file=sys.stderr)
exit(-1)
break
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