substituting values from constant matrix to matrix containing variables

Question

Neel 2013-11-23

评论： iamShreyans 2019-9-13

I am trying to substituting values from constant matrix to matrix containing variables in the equatinon

now 'dJ' is my matrix with variables {sina,cosb,tanc,cotd}

z_old is column matrix has values for {a,b,c,d} in dJ and every time the value changes

z_old = [1 2 3 4]' %initial values of states

while 1

z_new = z_old - s*dJ;

z_old=z_new;

end

Answer 1

Walter Roberson 2013-11-23

Providing that you are using the symbolic toolbox, see subs()

T = num2cell(z_old);
subs(Dj, {sina, cosb, tanc, cotd}, T)

iamShreyans 2019-9-13

Hi, I have a similar problem but your solution doesn't seem to work for me

I have a matrix t = [t1 t2 t3-90], where t1, t2 and t3 are syms variable.

I wish to set all t's to zero value and for this I wrote:

subs(t,{t1, t2, t3},{0, 0, 0})

But the 't' matrix still has the old values. I expected it to change to [0 0 -90] but it didn't happen.