/prog/ - Attn: physics (under-)graduates

Name: Anonymous 2012-10-27 8:09

No more error calculations!

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Name: Anonymous 2012-10-27 11:58

Consider

stdev(e, [vs]) := block([d, s, r],

d : lambda([s], concat('\\Delta\ , s)),

s : sqrt(apply("+", map(lambda([v], (diff(e, v[1]) * d(v[1]))^2), vs))),

r : at([e, s], apply(append, map(lambda([v], [v[1]=v[2], d(v[1])=v[3]]), vs))),

print("== LaTeX expression for the error =="),

print(tex1(factor(s))),

print("== Value of the expression =="),

print(r[1], "\\pm", r[2]),

false)$

stdev(x^2/log(y), [x, 15.46, 0.01], [y, 3.0, 0.1])$

Why did you use base64 and not just code tags?

#!/usr/bin/env python

from sys import *

import subprocess



def cmd(args, data):

    return subprocess.Popen(args, shell=False,

                            stdin=subprocess.PIPE,

                            stdout=subprocess.PIPE,

                            stderr=subprocess.PIPE).communicate(data)[0]



def texmax(e):

    return cmd(["maxima", "--very-quiet"],"tex(%s,false);" % e).replace(

        '\n','').replace(r'\it delta\_',r'\Delta ').strip(' $')



def subst(va, expr):

    for v in va:

        name, value, error = v

        expr = "subst(%s,%s,%s)" % (value, name, expr)

        expr = "subst(%s,%s,%s)" % (error, 'delta_'+name, expr)

    return expr



def do_it(expr, variables):

    

    expr='(%s)'%expr

    errexpr=[]

    for v in variables:

        name=v[0]

        errexpr.append("(derivative(%s,%s)*delta_%s)^2" % (expr,name,name))

    errexpr = "sqrt(%s)" % (' + '.join(errexpr))

    

    print '== LaTeX expression for the error =='

    print texmax("factor(%s)" % errexpr)

    print '== Value of the expression =='

    print r'\pm'.join( map(lambda e: texmax('float(%s)' % subst(variables,e)),

        [expr,errexpr]) )



def main():

    a = argv[1:]

    if len(a)==0:

        print '''Usage: errors.py expression [variable:value:error]...



Example: errors.py 'x^2/log(y)' x:15.46:0.01 y:3.0:0.1'''

        exit(1)

    expr = a[0]

    variables = map(lambda s:s.split(':'), a[1:])

    do_it(expr, variables)

    

main()

Name: Anonymous 2012-10-28 17:48

>>2
Wow, you are quite the Maxima genius! Thank you.

Why did you use base64 and not just code tags?
I've had a bad experience in the past where Shitchan messed it up.

Attn: physics (under-)graduates

1 Name: Anonymous 2012-10-27 8:09

2 Name: Anonymous 2012-10-27 11:58

3 Name: Anonymous 2012-10-28 17:48

Name: Anonymous 2012-10-27 8:09

Name: Anonymous 2012-10-27 11:58

Name: Anonymous 2012-10-28 17:48