Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

is it because of the sin and cos? how do i solve this?

clc;
clear all;
a1 = 150; alpha1 = pi/2; d1 = 470;
a2 = 600; alpha2 = 0; d2 = 0;
a3 = 120; alpha3 = pi/2; d3 = 720; 
syms c1 c2 c23 c3 c4 c5 c6 s1 c1 s2 s23 s3 s4 s5 s6 R03 R36 th1 th2 th3 th4 th5 th6 Xc Yc Zc R06 ox oz oy d6 r d D r11 r12 r13 r21 r22 r23 r31 r32 r33
c1 = cos(th1)
c2 = cos(th2)
c3 = cos(th3)
s1 = sin(th1)
s2 = sin(th2)
s3 = sin(th3)
c23 = cos(th2+th3)
s23 = sin(th2+th3)

d = a1
d6 = 5

%assume d6 = 5
R = [1 0 0 500;
    0 1 0 100;
    0 0 1 1500;
    0 0 0 1];
r11 = R(1,1)
r12 = R(1,2)
r13 = R(1,3)
r21 = R(2,1)
r22 = R(2,2)
r23 = R(2,3)
r31 = R(3,1)
r32 = R(3,2)
r33 = R(3,3)

ox = R(1,4)
oy = R(2,4)
oz = R(3,4)
Xc = ox - d6*R(1,3)
Yc = oy - d6*R(2,3)
Zc = oz - d6*R(3,3)
D = (Xc^2+Yc^2-d^2+(Zc-d1)^2-a2^2-a3^2)/(2*a2*a3)
%inverse kinematic 

th1 = atan2(Xc,Yc)
th2 = atan2(sqrt(Xc^2+Yc^2-d^2),Zc-d1)-atan2(a2+a3*c3*,a3*s3)
th3 = atan2 (D,sqrt((1-d^2)))
th4 = atan2(c1*c23*r13+s1*c23*r23+s23r33,-c1*s23*r13-s1*s23*r23+c23*r33)
th5 = atan2(s1*r13-c1*r23,sqrt(1-(s1*r13-c1*r23)^2))
th6 = atan2(-s1*r11+c1*r21, s1*r12-c1*r22)


Error: File: HW2_Q3.m Line: 44 Column: 55
Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

Answer 1

[Walter Roberson]

In your line

th2 = atan2(sqrt(Xc^2+Yc^2-d^2),Zc-d1)-atan2(a2+a3*c3*,a3*s3)
                                                     ^

you have a * without a following item to be multiplied by.