How to replace any value into vector or matrix to -inf

 ab =

   11.0000
   11.5000
   12.0000
   12.1000
   12.2000
   12.3000
   11.2000
    9.0000
    9.5000
   11.3000

 ab<10

 ans =

Columns 1 through 9

     0     0     0     0     0     0     0     1     1

Column 10

     0

 ab1

ab1 =

Columns 1 through 5

   11.0000   11.5000   12.0000   12.1000   12.2000
   11.1000   11.4000   12.0000   12.1000   12.2000

Columns 6 through 10

   12.3000   11.2000    9.0000    9.5000   11.3000
   12.3000   11.2000    9.0000    9.5000   11.3000

>> ab1<10

ans =

Columns 1 through 9

     0     0     0     0     0     0     0     1     1
     0     0     0     0     0     0     0     1     1

Column 10

     0
     0

i want to replace ab<10 to -inf, without loop, and other variables and matrix size remains same. It should be applicable to any type of matrix.

Answer 1

[Walter Roberson]

ab(ab<10) = -inf;

[Triveni]

Sir, If i need to be make other matrix's index -inf then how can i do?.

 f_data =

    1.0000
   13.5000
   11.0000
   12.1000
   12.2000
   13.3000
   11.2000
   13.0000
   13.5000
    8.3000

In both matrices any index<10, i have to make both corresponding matrix -inf.

[Walter Roberson]

mask = ab<10 | f_data<10;
a(mask) = -inf;
f_data(mask) = -inf;