Matlab基础操作笔记[2]-sym()、vpa()、int()
sym()
创建符号变量、表达式、功能、矩阵
sym()讲 符号变量、表达式、功能、矩阵 以数学形式创建变量。
示例如下:(截取自Create symbolic variables, expressions, functions, matrices – MATLAB sym – MathWorks 中国)
创建符号变量
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创建符号矢量
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创建符号矩阵
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创建符号多维阵列
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创建符号数字
将数字值转换为符号数字或表示式。用于次表达,而不是整个表达,以获得更好的准确性。在整个表达式上使用是不准确的,因为 MATLAB 首先将表达方式转换为浮动点数字,从而失去准确性。 不能总是恢复这种丢失的准确性。
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剩下几种情况省略。
vpa()
可变精度算术(任意精度算术)Variable-precision arithmetic (arbitrary-precision arithmetic) – MATLAB vpa – MathWorks 中国
vpa()可以把sym类的标识转化位浮点数。
示例:
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int()
用于积分
用法,参考自:Definite and indefinite integrals – MATLAB int – MathWorks 中国
F = int(
computes the indefinite integral of expr
)expr
. int
uses the default integration variable determined by symvar
(expr,1
). If expr
is a constant, then the default integration variable is x
.
参数只有函数expr的积分,默认积x
F = int(
computes the indefinite integral of expr
,var
)expr
with respect to the symbolic scalar variable var
.
函数expr积var
F = int(
computes the definite integral of expr
,a
,b
)expr
from a
to b
. int
uses the default integration variable determined by symvar
(expr,1
). If expr
is a constant, then the default integration variable is x
.
int(expr,[a b])
is equivalent to int(expr,a,b)
.
从a到b积expr,默认积x
F = int(
computes the definite integral of expr
,var
,a
,b
)expr
with respect to the symbolic scalar variable var
from a
to b
.
int(expr,var,[a b])
is equivalent to int(expr,var,a,b)
.
函数expr从a到b积var
示例:
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