awk - Bash: nested for loop to iterativly change a paritular element in a matrix -

i try change in file.txt formatted follow:

0.0 0.0 1.0 2.0 3.0 0.0 0.0 3.0 3.0 35.0  ... 

only second zeros in each lines: 0.0 numbers.

i know sed command change elements if write that:

input=0    f in {0..2}        sed -i "1s/$input/$f/" file.txt  input=$f done 

the sed command change first 0 in file, changing to:

1.0 0.0 1.0 2.0 3.0 1.0 0.0 3.0 3.0 35.0 ... 

but, instead, like:

0.0 0.1 1.0 2.0 3.0 0.0 0.1 3.0 3.0 35.0 ... 

so how can specify sed must change number?

upgrade:

i try use sed command guessed sadasidha:

number=0.2 sed -r "s/^([0-9].[0-9]) ([0-9].[0-9])/\1 ${number}/" input.txt 

but request bit different, idea make loop in can increment second element on fourth line, instance, 10 times, second element of third line, second line , first one...as in 4 loop as:

input=0      f in {0..10}        m in {0..10}         s in {0..10}          g in {0..10}                 change second element on fourth line 10 times,      input=$f     done         change second element on third line 10 times,      input=$m     done .... 

so can have 11^4 different values of elements in second rows each combination of numbers put inside loop (i.e.: between 0,10).

this job awk. default awk splits of sequences of whitespaces ([[:space:]]+). once awk reads line, splits line on default delimiter , assigns them variables can referenced using $ , column number.

for example:

$ cat file 0.0 0.0 1.0 2.0 3.0 0.0 0.0 3.0 3.0 35.0 

$ awk '{$2=($2==0?0.1:$2)}1' file 0.0 0.1 1.0 2.0 3.0 0.0 0.1 3.0 3.0 35.0 

we increment value of second column using $2 , 1 @ end allows print line. can right as:

$ awk '{$2=($2==0?0.1:$2); print}' file 0.0 0.1 1.0 2.0 3.0 0.0 0.1 3.0 3.0 35.0