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Timeline

My development logbook

Current Time in Objective-c and Python

To get the current time in python

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>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2014, 3, 6, 18, 51, 13, 321003)

and in objective-c

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NSDate* date = [NSDate date];
NSLog(@"%@", date);

SpaceX and Redundancy

Q: So, these flight computers on Dragon – there are three on board, and that’s for redundancy?

A: There are actually six computers. They operate in pairs, so there are three computer units, each of which have two computers checking on each other. The reason we have three is when operating in proximity of ISS, we have to always have two computer strings voting on something on critical actions. We have three so we can tolerate a failure and still have two voting on each other. And that has nothing to do with radiation, that has to do with ensuring that we’re safe when we’re flying our vehicle in the proximity of the space station.

I went into the lab earlier today, and we have 18 different processing units with computers in them. We have three main computers, but 18 units that have a computer of some kind, and all of them are triple computers – everything is three processors. So we have like 54 processors on the spacecraft. It’s a highly distributed design and very fault-tolerant and very robust.

Source

How to Make a Label Recognise a Tape

Step 1) Need to implement a selector to handle the gesture recognizer’s callback

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-(void) handleSingleTap:(UIGestureRecognizer *)gestureRecognizer  {
    NSLog(@"handleSingleTap called");
}

Step 2) Create and assign a gesture recognizer to a UILabel

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    UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    [self.lblHour addGestureRecognizer:singleTap];

Step 3) Important Must make sure setUserInteractionEnabled of the UILabel is set

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    [self.lblHour setUserInteractionEnabled:YES];

Yield to Maturity

Yield to maturity (YTM) is sometimes known simply as “yield”, “redemption yield” or “gross redemption yield” (GRY) because it is the yield to the redemption date assuming all cashflows are paid gross (no tax deduction for example).

It is the internal rate of return of a bond – the yield necessary to discount all the bond’s cashflows to an NPV equal to its current price

Quick 32nd Lookup

32nd Decimal
1/32 0.03125
2/32 0.0625
3/32 0.09375
4/32 0.125
5/32 0.15625
6/32 0.1875
7/32 0.21875
8/32 0.25
9/32 0.28125
10/32 0.3125
11/32 0.34375
12/32 0.375
13/32 0.40625
14/32 0.4375
15/32 0.46875
16/32 0.5
17/32 0.53125
18/32 0.5625
19/32 0.59375
20/32 0.625
21/32 0.65625
22/32 0.6875
23/32 0.71875
24/32 0.75
25/32 0.78125
26/32 0.8125
27/32 0.84375
28/32 0.875
29/32 0.90625
30/32 0.9375
31/32 0.96875
32/32 1.0