matlab - while loop until values converge -


i need solve following equation:

old_val = 0.4*u_z/(log(5/new_val));

where 

new_val = 0.11*1.5e-5./old_val;

in order calculate new_val , old_val need write loop calculates new_val , old_val , takes true value of new_val when new_val 0.001% of previous new_val.

i have though using while loop this, think might work. bit confused, though, on how start while loop, should have:

while abs((new_val(i) - val_prev(i))) > 0.000001          old_val = 0.4*w(i)/(log(5/new_val));     dummy = new_val(i);     new_val = 0.11*1.5e-5./old_val;     val_prev(i) = dummy; end

or

    while abs((new_val(i) - val_prev(i))) / abs(val_prev(i)) > 0.000001          old_val = 0.4*w(i)/(log(5/new_val));     dummy = new_val(i);     new_val = 0.11*1.5e-5./old_val;     val_prev(i) = dummy; end

where 

val_prev = new_val*1.1;

which used initiate iteration. while loop used continue running loop until new_val , val_prev within 0.001% of each other.

if understand correctly, want solve equation x: 

x =  0.4*u_z/log( 5/(0.11*1.5e-5./x) )

with u_z constant. if indeed want do, i'd re-write as

x * log( 5*x/1.65e-6 ) - 0.4*u_z == 0

and solve this: 

x_sol = fzero(@(x) x .* log( 5*x/1.65e-6 ) - 0.4*u_z, 1)

or, if insist, use own newton-raphson scheme:

fx   = @(x) x .* log( 5*x/1.65e-6 ) - 0.4*u_z dfdx = @(x) log(x) + 15.9242;  x = 1; f = fx(x); while abs(f) > 1e-6        x = x-f/dfdx(x);     f = fx(x); end

but i'm not sure if want...


Comments

Post a Comment

Popular posts from this blog

python - How to create a legend for 3D bar in matplotlib? -

Image
given ax = plt.subplot() : ax.bar()[0] can passed plt.legend() . however, ax.bar3d() returns none . how create legend displayed bars? update: passing legend="stuff" ax.bar3d() , calling ax.legend() raises /usr/lib/python2.6/site-packages/matplotlib/axes.py:4368: userwarning: no labeled objects found. use label='...' kwarg on individual plots. warnings.warn("no labeled objects found. " you need use proxy artist legends not supported. this code: from mpl_toolkits.mplot3d import axes3d import matplotlib.pyplot plt import numpy np fig = plt.figure() ax = fig.add_subplot(111, projection='3d') x, y = np.random.rand(2, 100) * 4 hist, xedges, yedges = np.histogram2d(x, y, bins=4) elements = (len(xedges) - 1) * (len(yedges) - 1) xpos, ypos = np.meshgrid(xedges[:-1]+0.25, yedges[:-1]+0.25) xpos = xpos.flatten() ypos = ypos.flatten() zpos = np.zeros(elements) dx = 0.5 * np.ones_like(zpos) dy = dx.copy() dz = hist.flatten() ax...
Read more

java - Multi-Label Document Classification -

i have database in store data based upon following 3 fields: id, text, {labels}. note each text has been assigned more 1 label \ tag \ class. want build model (weka \ rapidminer \ mahout) able recommend \ classify bunch of labels \ tags \ classes given text. i have heard svm , naive bayes classifier, not sure whether support multi-label classification or not. guides me right direction more welcome! the basic multilabel classification method one-vs.-the-rest (ovr), called binary relevance (br). basic idea take off-the-shelf binary classifier, such naive bayes or svm, create k instances of solve k independent classification problems. in python-like pseudocode: for each class k: learner = svm(settings) # example labels = [class_of(x) == k x in samples] learner.learn(samples, labels) then @ prediction time, run each of binary classifiers on sample , collect labels predict positive. (both training , prediction can done in parallel, since problems assumed ...
Read more

php - Dynamic url re-writing using htaccess -

how can rewrite http://mydomain.com/test/master.php?catid=2&subcatid=8 http://mydomain.com/test/master.php/catname/subcat using .htaccess file. once rewritten, how can access these parameters in master.php? note: untested, let me know if doesn't work. rewriterule ^master.php/([a-za-z0-9_-]+)/([a-za-z0-9_-]+)$ /master.php?catid$1&subcatid=$2 [l]
Read more