tikz-pgf
I'm trying to put two object randomly in a shape, the presence of first object is approximately 50% , and also the same for the second object. So this is why i need to use the rand value.
For example I will try to test if the value of rand is greater than 0.5*RAND_MAX then put object one, else put object two.
So the question is: What is the interval in which the value of rand lies within?
Yes, the rounded corners key can be specified at several points along the path with different values by adding [rounded corners=<value>] in the path, which will then be active until the end of the path or until the next rounded corners key. Alternatively, as Qrrbirlbel pointed out in a comment, you can also keep the option local to part of the path by enclosing it in { ... }. I've used both approaches in the example below:
\documentclass[border=5mm]{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
\filldraw[draw=blue!50, fill=black!10, rounded corners=3] (1.9,15)
-- (3.1,15) {[rounded corners=1]
-- (3.1,14.6)
-- (3.3,14.6)}
-- (3.3,15.2)
-- (3.5,15.2)
-- (3.5,13.9)
-- (3.3,13.9) [rounded corners=1]
-- (3.3,14.5)
-- (3.1,14.5) [rounded corners=3]
-- (3.1,14.1) -- (1.9,14.1) -- cycle;
\end{tikzpicture}
\end{document}
Since no further ideas seem to be readily forthcoming, I'll convert percusse's comment (above) into an accepted answer, and close this question...
You don't need
ifthen, Use for example,\pgfmathparse{(\weight>0.5)?1:0}\ifdim\pgfmathresult pt>0pt\node[circle, inner sep=1pt, fill=black] (\i) at (\x,\y) {};\fi
[All credit to percusse]
Best Answer
Between -1 and 1, distributed uniformly.
See section 89.3.6 Pseudo random functions of the TikZ manual for descriptions of the (pseudo-)random number generators.