# Solving for variables in matlab

1. Apr 2, 2009

### Dell

i need to make a code that can sole the following, finding the value of Sz
given the following vectors

S=[ -6, -6, -Sz]
P=[ 0 -6 -3]
Q=[ 5 4 -9]

i need to make a code that can find Sz so that
a)S $$\bot$$P
b)S$$\bot$$Q
c)S$$\bot$$(PxQ)
d)(SxP)$$\bot$$Q

i have managed to make matlab give me a condition for $$\bot$$, for example, what i set up is:

>>Sz=sym('Sz');
>>S=[ -6, -6, -Sz];
>>P=[ 0 -6 -3];
>>Q=[ 5 4 -9];

matlab returns

36+3*Sz

and i know that answer=0, therefore Sz=-12, but how do i get MATLAB to tell me that Sz=-12??

2. Apr 17, 2009

### swraman

build a string that is

'36+3*Sz = 0'

teh num2sr() command may help if the answer is not 0 all the time

then its just:
>> solve('36+3*Sz = 0')

Last edited: Apr 17, 2009