MATLAB: Subtraction of two single-precision arrays reuslts in an integer (?) array

arrayfloatintegerMATLABminussinglesubtraction

I have two 512×512 single-precision arrays (frame_1 and frame_2). Typing the name of either of these in the console shows the block of expected 5-digit numbers: 2.1799, -1.1602, 2.7134, 0.6899, …
When I try to take the difference (frame_diff = frame_2 – frame_1), the displayed frame_diff array now shows as all integers, even though Matlab claims it's also a single (as it should be!). I thought it was just a console display issue, but when I try options such as format shortEng, the frame_diff numbers indeed seem to be integers (or at least rounded floats!).
What gives? I found nothing in the Matlab array subtraction documentation that would explain what's happening here. The same thing happens with minus(frame_1, frame_2), by the way.

Best Answer

Values in your arrays frame_1 & frame_2 are such that, difference is always a whole number (fraction part is 0). So they appear as integer.
For example:
frame_1(1,1) --> -0.8467
frame_2(1,1) --> 3.1533
frame_1(1,1) - frame_2(1,1) --> -4
frame_1(1,2) --> -5.9399
frame_2(1,2) --> -0.9399
frame_1(1,2) - frame_2(1,2) --> -5
frame_1(1,3) --> 6.8799
frame_2(1,3) --> -4.1201
frame_1(1,3) - frame_2(1,3) --> 11
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