## How can I merge vector elements into a single number of type double?

Asked by Lazaros Ioakeimidis

### Lazaros Ioakeimidis (view profile)

on 4 Feb 2019
Latest activity Commented on by Guillaume

### Guillaume (view profile)

on 5 Feb 2019
Accepted Answer by Guillaume

### Guillaume (view profile)

Hello,
How can I transform this vector:
v=[1 2 3]
into this scalar of type double?:
k=123
Thank you,
Lazaros.

### Guillaume (view profile)

on 4 Feb 2019
Edited by Guillaume

### Guillaume (view profile)

on 4 Feb 2019

k = polyval(v, 10)
is probably the easiest.
This assume of course that each element of v is an integer in the range [0-9].

on 4 Feb 2019
Edited by Jan

### Jan (view profile)

on 4 Feb 2019

x = [1,2,3];
d = x * 10 .^ (numel(x)-1:-1:0).' % dot product

on 4 Feb 2019
Edited by YT

### YT (view profile)

on 4 Feb 2019

Something like this?
A = [1 2 3];
joined = str2num(strjoin(num2cell(num2str(A(:))),''));
%>> joined = 123 (type double)
There are probably some more elegant solutions, but this is what I came up with for now.

Guillaume

### Guillaume (view profile)

on 4 Feb 2019
If you were going to go through strings and back, this would be simpler and faster:
str2num(char(A + '0'))
However, conversion of numbers to/from strings are slow (compared to just doing maths)
YT

### YT (view profile)

on 4 Feb 2019
Looks much better. Thanks, learned something new today. The only downside to this is that, like you stated in your polyval solution, that this also only works correctly for positive integers.
Guillaume

### Guillaume (view profile)

on 5 Feb 2019
Indeed but that is most likely the case I assume.
A simpler, yet more generic solution, using number->string->number conversion:
str2num(strjoin(compose('%d', A), ''))