I need an advice at my project

Hey,i want to make a straight line at a 5 bar linkage robot arm but something is wrong with my code

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#include <Servo.h>
struct xyzPos{ //a struct to hold multple returned arguments for the 3D position
float x;
float y;
float z;
};

void setup()
{
struct xyzPos currentPos; //current location of tip of arm
struct xyzPos desiredPos; //desired location of tip of arm

}

void loop()
{

xyzPos kinematics();
}
struct xyzPos kinematics(float thita1, float thita2)
{
Serial.println(“in kinematics”);
struct xyzPos POS;
float L1=5;
float L2=6;
float L3=5;
float L4=6;
float L5=4;

thita1 = (30 * PI /180);
thita2 = (30 * PI /180);

POS.x=L1cos(thita1)+L2(cos(thita1+thita2));
POS.y=L1sin(thita1)+L2(sin(thita1+thita2));
POS.z=thita1+thita2;

return POS;

}

Do not double post.