round

Round fi object toward nearest integer or round input data using quantizer object

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Syntax

y = round(a)
y = round(q,x)

Description

example

y = round(a) rounds fi object a to the nearest integer. In the case of a tie, round rounds values to the nearest integer with greater absolute value. The rounded value is returned in fi object y.

example

y = round(q,x) uses the RoundingMethod and FractionLength settings of quantizer object q to round the numeric data x, but does not check for overflows during the operation. Input x must be a built-in numeric variable. Use the cast function to work with fi objects.

Examples

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Open Live Script

The following example demonstrates how the round function affects the numerictype properties of a signed fi object with a word length of 8 and a fraction length of 3.

a = fi(pi,1,8,3)
a = 
    3.1250

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 8
        FractionLength: 3

y = round(a)
y = 
     3

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 6
        FractionLength: 0

The following example demonstrates how the round function affects the numerictype properties of a signed fi object with a word length of 8 and a fraction length of 12.

a = fi(0.025,1,8,12)
a = 
    0.0249

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 8
        FractionLength: 12

y = round(a)
y = 
     0

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 2
        FractionLength: 0
Open Live Script

This example shows how to use the rounding method and fraction length specified by quantizer object q to round the numeric data in x.

q = quantizer('fixed','convergent','wrap',[3 2])
q =


        DataMode = fixed
       RoundMode = convergent
    OverflowMode = wrap
          Format = [3  2]

x = (-2:eps(q)/4:2)';
y = round(q,x);
plot(x,[x,y],'.-'); axis square

Open Live Script

The functions convergent, nearest, and round differ in the way they treat values whose least significant digit is 5.

  • The convergent function rounds ties to the nearest even integer.

  • The nearest function rounds ties to the nearest integer toward positive infinity.

  • The round function rounds ties to the nearest integer with greater absolute value.

This example illustrates these differences for a given input, a.

a = fi([-3.5:3.5]');
y = [a convergent(a) nearest(a) round(a)]
y=8×4 object
   -3.5000   -4.0000   -3.0000   -4.0000
   -2.5000   -2.0000   -2.0000   -3.0000
   -1.5000   -2.0000   -1.0000   -2.0000
   -0.5000         0         0   -1.0000
    0.5000         0    1.0000    1.0000
    1.5000    2.0000    2.0000    2.0000
    2.5000    2.0000    3.0000    3.0000
    3.5000    3.9999    3.9999    3.9999

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 16
        FractionLength: 13

Input Arguments

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Input fi array, specified as scalar, vector, matrix, or multidimensional array.

For complex fi objects, the imaginary and real parts are rounded independently.

round does not support fi objects with nontrivial slope and bias scaling. Slope and bias scaling is trivial when the slope is an integer power of 2 and the bias is 0.

Data Types: fi
Complex Number Support: Yes

RoundingMethod and FractionLength settings, specified as a quantizer object.

Example: q = quantizer('fixed', 'round', [3 2]);

Input array to quantize using the quantizer object q, specified as a scalar, vector, matrix, or multidimensional array.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical
Complex Number Support: Yes

Algorithms

  • y and a have the same fimath object and DataType property.

  • When the DataType property of a is single, double, or boolean, the numerictype of y is the same as that of a.

  • When the fraction length of a is zero or negative, a is already an integer, and the numerictype of y is the same as that of a.

  • When the fraction length of a is positive, the fraction length of y is 0, its sign is the same as that of a, and its word length is the difference between the word length and the fraction length of a, plus one bit. If a is signed, then the minimum word length of y is 2. If a is unsigned, then the minimum word length of y is 1.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

See Also

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Introduced before R2006a

Fixed-Point Designer Documentation

Support