Sorry for the dumb question.  I'm having some trouble figuring out how to define an inner product on this space.  The space is $C[a, b]$ and the norm here is defined by $\|f\| = \sup_{a \leq x \leq b}|f(x)|$.    I know that $\|f\|^2 = \langle f, f \rangle$ but what about more generally $\langle f, g \rangle$?  I hope my question makes sense.
Show that a norm on an inner product space satisfies parallelogram law. Hence use the parallelogram law to show that the space of continuous real functions defined on the interval $[a,b]$ is not a Hilbert space. Here I did the first part. Let $X$ be an inner product space and $x,y\in X$ consider $\Vert x+y\Vert ^2$ and $\Vert x-y\Vert ^2$ Then on adding I get $\Vert x+y\Vert ^2+\Vert x-y\Vert ^2=2(\Vert x\Vert ^2 +\Vert y\Vert ^2)$ For the second part I don’t know how can a parallelogram law prove $C[a,b]$ is not a Hilbert space, help me please.
I made the jump from Jumsoft's Money app to GnuCash a while back. It appealed to all my OCD tendencies. I don't know how to use Perl, or stuff of the sort, but with detailed instructions I manage to get things done... when I can find them.  I set up Finance::Quote to pull quotes after I set up GnuCash. I even managed to get it to pull quotes for Korean funds. And every thing had been working well, until tonight. I only get back a pop-up that states "There was an unknown error while retrieving the price quotes." That's where I need help. What can I do?  I dug around and found that it seems that it has something to do with Yahoo Finance ending it's API support. I also learned that Finance::Quote can pull data from many sources, so I don't really understand why one missing API would break it. I also saw that someone out there is trying to use AEX to pull the quotes instead for GnuCash specifically. I found Finance::Quote on cpan (I also first heard of cpan), but I don't understand what I'm looking at. But that's all beside the point. I don't know how to fix this.  Any help would be appreciated. I'm on Windows 10, GnuCash version 2.6.17, and have Strawberry Perl 5.18.2.2-32bit installed.  edit Thanks everyone who responded. It seems to be working more or less. The currency and Korean funds still haven't updated, but you've shown this horse to water. I'll do my best to drink it now. Java Strings: "String s = new String("silly");" I need to know what the original account was for my Clash of Clans is so I may transfer to another device. Any suggestions? I have tried multiple times trying to find through my emails with no luck. Can Game Center email a list of my CoC account? Mann-Whitney U test with unequal sample sizes Repeat String - Javascript What is the best or most concise method for returning a string repeated an arbitrary amount of times?  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Here's an example:  class A(object):     _dict = dict()      def __new__(cls):         if 'key' in A._dict:             print "EXISTS"             return A._dict['key']         else:             print "NEW"             return super(A, cls).__new__(cls)      def __init__(self):         print "INIT"         A._dict['key'] = self         print ""  a1 = A() a2 = A() a3 = A()   Outputs:  NEW INIT  EXISTS INIT  EXISTS INIT   Why? I am developing an application and can not figure out a proper abstract term that would fit an interface that defines an object as Movable and Resizable (In essence, something that has a defined size and defined position). Calling it Movable and resizable is kind of silly. Layout was a term that came to my mind but it is not good as layout is something that is responsible for defining position and size, not containing it. Thanks a lot. I have had a question since childhood.  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