error when calling a function inside of another function

I'm very new to matlab function. so sorry if i asked a stupid question. i got an error saying "The expression to the left of the equals sign is not a valid target for an assignment." for the line as:

answer = function2(x,y,z);

in function1. when I run another .m file which call this function1 and this function1 calls function2 like the above. I've tested the function2 at the command line with no error. which returns a (1,3) vector. and in function1, i didn't define the variable "answer". I tried to modify the function2 to make it return 3 output variable with each being a scalar and even reduce the function2 output to only one scalar output, it still gave the same error. could anybody give me some help? I really appreciate that.

[Walter Roberson]

Please show us the exact code line. There might be something subtle about what you used.

Answer 1

[Oleg Komarov]

In orbit, line 16, you open a { and close } before the end, last line. Remove them.

Then variables r0 and a are not defined anywhere in the function.

Oleg

Answer 2

[newbie]

ok, here is the function1 and the e_field() is the function2,thanks

function [pos_arr]=orbit(qom_in, pos, vel, dt)

    x(1:3)  = pos(1);
    y(1:3)  = pos(2);
    z(1:3)  = pos(3);      
    vx(1:3)  = vel(1);
    vy(1:3)  = vel(2);
    vz(1:3)  = vel(3);

                pos_arr = [];   
    ii      = 1;  
        rad     = sqrt(x(1)^2 + y(1)^2);
    rho     = sqrt((rad - r0)^2 + z(1)^2);    

      while((rad<(r0+a))&&(rad>(r0-a))&&(rho<a)){
    
      e  = e_field(x(1), y(1), z(1));
      b  = b_field(x(1), y(1), z(1));
    ax(2:4)  = ax(1:3);
    ay(2:4)  = ay(1:3);
    az(2:4)  = az(1:3);
    vx(2:4)  = vx(1:3);
    vy(2:4)  = vy(1:3);
    vz(2:4)  = vz(1:3);
    x(2:4)  = x(1:3);
    y(2:4)  = y(1:3);
    z(2:4)  = z(1:3);
        
    ax(1)  = qom_in*(e(1) + vy(1)*b(3) - vz(1)*b(2));
    ay(1)  = qom_in*(e(2) + vz(1)*b(1) - vx(1)*b(3));
    az(1)  = qom_in*(e(3) + vx(1)*b(2) - vy(1)*b(1));

    vx(1)  = vx(2) + (ax(1) + ax(2))*dt/2;
    vy(1)  = vy(2) + (ay(1) + ay(2))*dt/2;
    vz(1)  = vz(2) + (az(1) + az(2))*dt/2;
          
    x(1)  = x(2) + (vx(1) + vx(2))*dt/2;
    y(1)  = y(2) + (vy(1) + vy(2))*dt/2;
    z(1)  = z(2) + (vz(1) + vz(2))*dt/2;

    ii      =ii+1;  
                rad     = sqrt(x(1)^2 + y(1)^2);
    rho     = sqrt((rad - r0)^2 + z(1)^2);     

                pos_arr = [pos_arr; [x(1), y(1), z(1)]];
      }end

Answer 3

[newbie]

thanks a lot.