# How to substitute multiple values in symbolic matrix?

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Hi, How to substitute multiple values in symbolic matrix? With function subs, we can substitute only single value in expression. Writing nested subs(subs(...)) can work but it becomes tedious. Here is sample code:
syms x y z w
N=[ 1y+y+z,x/2 - y/3 + z/3, x*y, x+z];
Is there any way to substitute values to w,x,y,z in single line? I guess then I have to define variables like x(1), x(2) etc. and have to use for loop to change values. Is this approach correct or is there any better way?

### 采纳的回答

Andrei Bobrov 2013-11-29
syms x y z w
N=[ w+y+z,x/2 - y/3 + z/3, x*y, x+z]
X = sym(['[',sprintf('X(%d) ',1:4),']'])
out = subs(N,[x, y, z, w],X)
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Karan Gill 2016-12-8
>> syms x y z w
N=[ 1*y+y+z,x/2 - y/3 + z/3, x*y, x+z];
vars = [w x y z];
newVars = sym('x%d',[1 4]);
subs(N,vars,newVars)
ans =
[ 2*x3 + x4, x2/2 - x3/3 + x4/3, x2*x3, x2 + x4]
Much easier to read and understand. Look up the doc for sym to understand the command I used: https://www.mathworks.com/help/symbolic/sym.html

### 更多回答（1 个）

Youssef El Seblani 2018-3-31

clc
clear
syms x y z w
N=[ w+y+z,x/2 - y/3 + z/3, x*y, x+z]
A=sym('X',[1,4])
N(A) = subs(N,[x, y, z, w],A)
for example
N(1,2,3,4)
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