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

Hello,

How can I transform this vector:

v=[1 2 3]

into this scalar of type double?:

k=123

Thank you,

Lazaros.

Answer 1

[Guillaume]

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].

Answer 2

[Jan]

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

Answer 3

[YT]

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]

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]

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]

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), ''))