MATLAB 中的数值类型

MATLAB 中的 Numeric 类包括有符号和无符号整数、单精度浮点数和双精度浮点数。通常，MATLAB 将所有数值存储为双精度浮点数。但是，我们可以选择将任何数字或数字数组存储为整数或单精度，以获得更好的内存利用率。所有数值类型都允许基本的数组操作，例如索引等。

创建数值变量：

Data type	Description	Size	Typical range
double	Double-precision  (floating-point values)	8 byte	+/- 1.7e +/- 308 (~15 digits)
single	Single-precision  (floating-point values)	4 byte	+/- 3.4e +/- 38 (~7 digits)
int8	8 bit signed integer	1 byte	-128 to 127
int16	16 bit signed integer	2 byte	-32768 to 32767
int32	32 bit signed integer	4 byte	-2147483648 to 2147483647
int64	Signed integer	8 byte	-(263) to (263)-1
uint16	Unsigned integer	2 byte	0 to 65535
uint32	Unsigned integer	4 byte	0 to 4294967295
uint64	Unsigned integer	8 byte	0 to 18,446,744,073,709,551,615

示例 1 ：

Matlab

% MATLAB code for Numeric Variables
gfg = single([4.4 3.9 6.9]) .* 8.4
gfg = double([4.4 3.9 6.9]) .* 8.4
gfg = int8([4.4 3.9 6.9]) .* 8.4
gfg = int16([4.4 3.9 6.9]) .* 8.4
gfg = int32([4.4 3.9 6.9]) .* 8.4
gfg = int64([4.4 3.9 6.9]) .* 8.4

输出：

gfg = 36.960  32.760   57.960
gfg = 36.960  32.760   57.960
gfg = 34  34  59
gfg = 34  34  59
gfg = 34  34  59
gfg = 34  34  59

数值类型的转换：

MATLAB 提供以下函数来转换为各种数值数据类型：

Data type	Description	Syntax
cast	Convert data type of one variable to other	B = cast ( A, newclass) B = cast (A , ‘like’,p)
typecast	Convert data type without changing underlying data	Y = typecast (X, type )

示例 2：

MATLAB

% MATLAB code for conversion of Numeric Types
gfg = int8([-5 5]);
b= cast(gfg, "uint8")

输出：

Ans: b = 0  5

示例 3：

MATLAB

% MATLAB code for conversion of Numeric Types
gfg = int16(-1)
X = typecast(gfg , 'uint16')

输出：

gfg = -1
X = 65535

查询类型和值：

MATLAB 提供以下数据类型来检查各种数值：

Data type	Description	Syntax
isinteger	Determine whether input is integer array	TF = isinteger(A)
isfloat	Determine if input is floating-point array	TF = isfloat(A)
isnumeric	Determine whether input is numeric array	TF = isnumeric(A)
isreal	Determine whether array uses complex storage	TF = isreal(A)
isfinite	Determine which array elements are finite	TF = isfinite(A)
isinf	Determine which array elements are infinite	TF = isinf(A)
isnan	Determine which array elements are NaN(Not a Number)	TF = isnan(A)

示例 4：

MATLAB

% MATLAB code for Query Type and Value
gfg = isinteger(4)
g = isfloat(pi)
fg = isreal(2 + 7i)
x = isfinite(1 ./0)
y = isinf(1./0)
z = isnan(0./0)

输出：

gfg = 0
g = 1
fg = 0
x = 0
y = 1
z = 1

数值限制：

MATLAB 提供以下类型来检查数值的限制：

Type	Description	Syntax
eps	Floating-point relative accuracy	d = eps d = eps(x) d = eps(datatype)
flintmax	Largest consecutive integer  in floating-point format	f = flintmax f = flintmax(precision)
Inf	Create array of all Inf values	X = Inf X = Inf(n) X = Inf(sz1,…,szN) X = Inf(sz) X = Inf(___,typename) X = Inf(___,’like’,p)
intmax	Largest value of specific integer type	v = intmax v = intmax(type)
intmin	Smallest value of specified integer type	v = intmin v = intmin(‘classname’)
NaN	Create array of all Not a Number values	X = NaN X = NaN(n) X = NaN(sz1,…,szN) X = NaN(sz) X =NaN(___,typename) X = NaN(___,’like’,p)
realmax	Largest positive floating-point number	f = realmax f = realmax(precision)
realmin	Smallest normalized floating-point number	f = realmin f = realmin(precision)

示例 5：

MATLAB

% MATLAB code for Numeric Value Limits
gfg = flintmax
gfg = intmax
gfg = Inf
gfg = intmin
gfg =NaN
gfg = realmax

输出：

gfg = 9.0072e+15
gfg = 2147483647
gfg = Inf
gfg = -2147483648
gfg = NaN
gfg = 1.7977e+308