Troubleshooting Integers in Matlab: Why Does 1019/250*250-1019 Not Result in 0?

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SUMMARY

The expression 1019 / 250 * 250 - 1019 in MATLAB does not yield zero due to floating-point arithmetic precision issues. MATLAB does not have a dedicated integer variable type, which leads to small rounding errors in calculations. To ensure integer outputs, users should utilize the fix() or floor() functions to round results appropriately. The int2str function inherently applies fix() to ensure integer representation.

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  • Knowledge of MATLAB functions: fix() and floor()
  • Basic concepts of numerical precision in programming
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gerben
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Does anyone have an idea why this expression in Matlab with integers does not give zero as an answer:

>> 1019 / 250 * 250 - 1019
ans = -1.1369e-013
 
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AFAIK, MATLAB doesn't specifically store an integer variable type.

If you need to be sure you have an integer output, use either:

fix(input)

or

floor(input)

to round it to the nearest or down to the next lowest integer.

Functions such as int2str automatically have a fix() in the command definition.
 

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