Change "matrix" to a scalar

I have this code

function put=Montecarlo(s0,k,r,sigma,t,n)

sum0=0;

sum1=0;

var=0;

for i=1:n

st=s0*exp((r-1/2*sigma^2)*t+sigma*randn(0,1)*sqrt(t));

h=max(k-st,0);

sum1=sum0+h/i;

if i>1

var=var*(1-(1/(i-1)))+i*(sum1-sum0)^2;

end

sum1=sum0;

end

put=exp(-r*t)*sum1

desviacion=sqrt(var)/sqrt(n)

intervalo=[put-1.96*desviacion,put+1.96*desviacion]

...

When I try to run, matlab thinks that sum0 and sum1 are matrices.

put(50,52,0.06,0.12,0.5,100)

Error using ^ (line 51)

Incorrect dimensions for raising a matrix to a power. Check that the matrix is square and the power is a scalar. To

perform elementwise matrix powers, use '.^'.

Error in put (line 10)

var=var*(1-(1/(i-1)))+i*(sum1-sum0)^2;

How can I solve this problem?

Answer 1

[Star Strider]

If you want to square the elements of ‘var’ use element-wise exponentiation (the ‘dot operator’).

var=var*(1-(1/(i-1)))+i*(sum1-sum0).^2;

See Array vs. Matrix Operations for details.

If you then want ‘var’ to be a scalar, sum it:

var=var*sum((1-(1/(i-1)))+i*(sum1-sum0).^2);

.