How to assign negative and positive values to specific numbers in array?

How would I flip the signs in the array? a = xp', where 'a' is the array.

ans =

    0.0581
    0.0562
    0.0544
    0.0525
    0.0506
    0.0488
    0.0469
    0.0450
    0.0431
    0.0412
    0.0394
    0.0375
    0.0356
    0.0338
    0.0319
    0.0300
    0.0281
    0.0262
    0.0244
    0.0225
    0.0206
    0.0188
    0.0169
    0.0150
    0.0131
    0.0112
    0.0094
    0.0075
    0.0056
    0.0038
    0.0019
         0
   -0.0019
   -0.0038
   -0.0056
   -0.0075
   -0.0094
   -0.0112
   -0.0131
   -0.0150
   -0.0169
   -0.0188
   -0.0206
   -0.0225
   -0.0244
   -0.0262
   -0.0281
   -0.0300
   -0.0319
   -0.0338
   -0.0356
   -0.0375
   -0.0394
   -0.0412
   -0.0431
   -0.0450
   -0.0469
   -0.0488
   -0.0506
   -0.0525
   -0.0544
   -0.0562
   -0.0581
   -0.0600
    I need all negative numbers to be positive and all positive numbers to be negative. Sign needs to flip after the zero in the middle of the array.

Answer 1

[KSSV]

Let a be your column matrix.

b = -a ;

Note that

-1X-1 = +1
-1X+1 = -1

[Zach Dunagan]

Thank you for your quick response.