i have to find distance between two projects and i have taken three attributes for this purpose which are size, project mode and a constant value.i have written code in matlab 7.but it gives error.plz see the folowing code and help me.

t = 17;

a =0;

b=0;

%size

effort = 12;

effort1=14;

if ((z=46) & (j=1.15))

a = effort;

end;

h=1;

h1 = 2;

% sum of importance weights of current project

s = z + j ;

b = s / t;

if ((z1=50) & (j1=1.15))

b = effort1;

end;

% sum of weights of previous project

e = z 1+ j1+ h1 ;

f = e / t;

p = 24.5 ;

g = f * p;

% distance

d = b - g;

disp(d)

error is:

??? Error: File: I:\MCS\MSc\matlabinstalled\work\efffff.m Line: 9 Column: 7

The expression to the left of the equals sign is not a valid target for an assignment.

plz help me to overcome this error.