MathViz: Math expression code visualizer

#!/usr/bin/python import cgi from urllib import quote # to get ply to work on MIT CSAIL ... import sys sys.path.insert(0, '/afs/csail.mit.edu/u/p/pgbovine/lib/python/') from expr2latex import expr2latex print "Content-type: text/html\n" print ''' MathViz: Math expression code visualizer ''' DEFAULT_EXPR = 'x = (-b + sqrt(b^2 - 4*a*c)) / (2*a)' form = cgi.FieldStorage() if form.has_key('expr'): expr = form['expr'].value else: expr = DEFAULT_EXPR success = True try: latexOutput = expr2latex(expr) except Exception: success = False print '' print ''' ''' % expr print '

' # debug only: #print '

Input:

' + `expr` + '

' if success: print ' $%s$ ' % quote(latexOutput) #print '

Output LaTeX source code:

' print '

' else: print '''

Uh oh, unable to render your input :(

Please check that it's valid MATLAB or C-style syntax (with balanced parentheses), or email your input to me at philip@pgbovine.net so that I can see what's up with it.

Check those parentheses ;) ''' print '

' print '

' ## nix the visualize button ... #def create_entry_OLD(expr): # return '%s ' % (expr, expr) def create_entry(expr, i): return '%s

' % (expr, i) print ''' Example equations:

These equations were taken directly from real MATLAB code. As you can see, they are much easier to understand and debug when visualized using MathViz.

''' % ( create_entry('1/(4*pi*(2*pi*f))*pr', 1), create_entry('2*a/b*c*(sin(pi*c/2)/(pi*c)/2)', 2), create_entry('(-1./(sqrt(-1)*2*pi*freq(k)*rho)).*(p1(:,k) - p2(:,k));', 3), create_entry('3/(2*pi*(numel(krs)-1)*log10(exp(1)))*(krs(end) - krs(1))', 4), create_entry('1/2*(real(pressure_recreated1{i_freq}.*conj(vr_recreated{i_freq})))', 5), create_entry('max(ceil( (2*pi*oasp_input.f/oasp_input.wi_cmin - 2*pi*oasp_input.f/oasp_input.wi_cmax)/ (pi/4/(Rmax*1000)) ), 10);', 6), create_entry('finite_diff = (func(x+delta)-func(x-delta))/(delta*2)', 7), create_entry('finite_diff = (func(x+delta)-func(x-delta))/delta*2', 8), create_entry('((ws./c).*(1-1/2*(2./((ws./c)*d)).^2))', 9), ) print ''' Currently supports:

MATLAB and C-style variable names: my_var_1
struct variables: record.field.sub_field
R data frame variables: frame$field
flattening of fractions: x / y / z / w
exponents: a^b
square root: sqrt(x/y)
unary minus: -x
parentheses: 2*(3*4)
comparisons: x <= 3 / y
array accesses using parens and braces (MATLAB) and brackets (C-style): A(5), A{5}, A[5]
function calls: fib(n-1) + fib(n-2)
elimination of redundant parentheses: ((x + y)) ^ (((z + w)))
MATLAB array accesses using colons and commas: A(i,j,k,:)
Python array accesses and slicing: A[3:-2]
MATLAB left divide: y \ x
MATLAB dot operators: x.*y, A.^b
MATLAB transpose: A.'
MATLAB Hermitian transpose: A' (same as A.' for real matrices)

Possible new features (if there is a demand):

One-click feedback mechanism for queries that are rendered incorrectly
Multi-dimensional arrays: A[3][5]
Selective rendering of an entire source file, not just of one line of code

MathViz was created by Philip Guo. If you have questions, bug reports, or suggestions, please contact me at philip@pgbovine.net

Special thanks to Kevin Cockrell for creating an early prototype, inspiring the creation of MathViz, doing beta testing, making feature requests, and providing example MATLAB code. ''' print ''' '''