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MATLAB数字

MATLAB 支持各种数字类,包括符号和无符号的整数及单精度和双精度浮点数。默认情况下,MATLAB 存储所有数值为双精度浮点数。

可以选择存储任何数字或数字为整数或单精度数字阵列。

所有的数字类型支持基本的数组运算和数学运算。

各种数字数据类型的转换

MATLAB提供各种数字数据类型转换为以下功能:

函数 目的
double Converts to double precision number
single Converts to single precision number
int8 Converts to 8-bit signed integer
int16 Converts to 16-bit signed integer
int32 Converts to 32-bit signed integer
int64 Converts to 64-bit signed integer
uint8 Converts to 8-bit unsigned integer
uint16 Converts to 16-bit unsigned integer
uint32 Converts to 32-bit unsigned integer
uint64 Converts to 64-bit unsigned integer

例子

创建一个脚本文件,并键入下面的代码:

x = single([5.32 3.47 6.28]) .* 7.5
x = double([5.32 3.47 6.28]) .* 7.5
x = int8([5.32 3.47 6.28]) .* 7.5
x = int16([5.32 3.47 6.28]) .* 7.5
x = int32([5.32 3.47 6.28]) .* 7.5
x = int64([5.32 3.47 6.28]) .* 7.5

当运行该文件,它显示了以下结果:

x =
   39.9000   26.0250   47.1000
x =

   39.9000   26.0250   47.1000
x =
   38   23   45
x =
     38     23     45
x =
          38          23          45
x =
                   38                   23                   45

例子

让我们扩展前面的例子多一点。创建一个脚本文件,并键入下面的代码:

x = int32([5.32 3.47 6.28]) .* 7.5
x = int64([5.32 3.47 6.28]) .* 7.5
x = num2cell(x)

当运行该文件,它显示了以下结果:

x =
          38          23          45
x =
                   38                   23                   45
x = 
    [38]    [23]    [45]

最小和最大整数

函数intmax() 和 intmin()返回的最大和最小的值,它可以表示所有类型的整数。

这两个功能整数数据类型作为参数,例如,intmax(int8) 或intmin(int64)最大值和最小值值,可以表示的整数数据类型并返回。 

例子

下面的例子说明如何得到最小值和最大值的整数。创建一个脚本文件,它编写以下代码:

% displaying the smallest and largest signed integer data
str = 'The range for int8 is:
	%d to %d ';
sprintf(str, intmin('int8'), intmax('int8'))
str = 'The range for int16 is:
	%d to %d ';
sprintf(str, intmin('int16'), intmax('int16'))
str = 'The range for int32 is:
	%d to %d ';
sprintf(str, intmin('int32'), intmax('int32'))
str = 'The range for int64 is:
	%d to %d ';
sprintf(str, intmin('int64'), intmax('int64'))
 
% displaying the smallest and largest unsigned integer data
str = 'The range for uint8 is:
	%d to %d ';
sprintf(str, intmin('uint8'), intmax('uint8'))
str = 'The range for uint16 is:
	%d to %d ';
sprintf(str, intmin('uint16'), intmax('uint16'))
str = 'The range for uint32 is:
	%d to %d ';
sprintf(str, intmin('uint32'), intmax('uint32'))
str = 'The range for uint64 is:
	%d to %d ';
sprintf(str, intmin('uint64'), intmax('uint64'))

当运行该文件,它显示了以下结果:

ans =
The range for int8 is:
	-128 to 127 
ans =
The range for int16 is:
	-32768 to 32767 
ans =
The range for int32 is:
	-2147483648 to 2147483647 
ans =
The range for int64 is:
	-9223372036854775808 to 9223372036854775807 
ans =
The range for uint8 is:
	0 to 255 
ans =
The range for uint16 is:
	0 to 65535 
ans =
The range for uint32 is:
	0 to 4294967295 
ans =
The range for uint64 is:
	0 to 1.844674e+19

最小和最大浮点数

这函数realmax() 和realmin() 返回的最大值和最小值的值,可以表示为浮点数。

这两个函数调用时的参数'单',返回的最大值和最小值值,可以代表单精度数据类型以及何时被称为'双'的参数,返回的最大值和最小值值,可以表示双精度数据类型。

实例

下面的例子说明如何获得最大和最小的浮点数。创建一个脚本文件,它编写以下代码:

% displaying the smallest and largest single-precision 
% floating yiibai number
str = 'The range for single is:
	%g to %g and
	 %g to  %g';
sprintf(str, -realmax('single'), -realmin('single'), ...
    realmin('single'), realmax('single'))
% displaying the smallest and largest double-precision 
% floating yiibai number
str = 'The range for double is:
	%g to %g and
	 %g to  %g';
sprintf(str, -realmax('double'), -realmin('double'), ...
    realmin('double'), realmax('double'))

当运行该文件,它会显示以下结果:

ans =
The range for single is:
	-3.40282e+38 to -1.17549e-38 and
	 1.17549e-38 to  3.40282e+38
ans =
The range for double is:
	-1.79769e+308 to -2.22507e-308 and
	 2.22507e-308 to  1.79769e+308