Parrot User’s Delay

Question

A simple code golf challenge similar to an already existing, but more complex one:

1. Wait for user to press enter.
2. Wait for user to press enter again.
3. Print the elapsed time between the 1. and 2.
4. Wait an equal amount of time
5. Print the actual elapsed time of 4.

Order of 3. and 4. is not important. Notice that the second printout entails actual timekeeping during the machine's delay; just outputting the desired delay is not enough.

The time outputs should be in seconds, with at least 10 ms resolution.

Answer 1

MATL, 14 bytes

This answer uses the current version of the language (3.1.0), which is earlier than the challenge.

jY`jZ`tDY`Y.Z`

Example

I tried to wait for about 1 second:

>> matl jY`jZ`tDY`Y.Z`
> 
> 
1.011063770698121
1.013172086910349

Explanation

j       % input string (will be empty)
Y`      % start a stopwatch timer      
j       % input string (will be empty) 
Z`      % read the stopwatch timer and push the value onto the stack    
tD      % duplicate, convert to string and display
Y`      % start a stopwatch timer (this doesn't produce any output)      
Y.      % pause the specified amount of time (which is at the top of the stack)
Z`      % read the stopwatch timer (will be implicitly displayed)  

Answer 2

R, 87 bytes

code

f=readline;s=Sys.time;f();q=s();f();e=(m=s())+(z=(m-q));while(s()<e)1;cat(z,"\n",s()-m)

example

> f=readline;s=Sys.time;f();q=s();f();e=(m=s())+(z=(m-q));while(s()<e)1;cat(z,"\n",s()-m)
> 1.343448     # 1 second wait plus 0.3s mental lag
> 1.358646

Answer 3

Matlab: 44 bytes ##

input('');tic;input('');t=toc
pause(t);toc-t

Output

t =
    1.8318
ans =
    1.8338

Explanation: input('') wait for enter, tic starts timer, t=toc display

Answer 4

Mathematica, 71 bytes

(b=InputString)[];a=(c=Print@*First)@(d=AbsoluteTiming)@b[];c@d@Pause@a

Needs to be run in v10.3 or higher. Good thing that symbols are first-class objects...

Answer 5

Bash + GNU utilities, 63

d=0
f(){ read;d=`date +%s.%N-$d|bc -l`;}
f
f
bc<<<$d/1
sleep $d