inverse kinematics solver problem

hi

i am pranesh. I have been trying to implement inverse kinematic solver for my custom 7 DOF robotic arm. There are couple of issues that i face;

1. the solution is incorrect when checked forward kinematic equation function that i created( this fk function has been tested multiple times), with significant offset
2. each time i invoke a function the solution shifts by huge value
3. Also i would like to elobrate on how weights affect the solution of the ik solver.

i have attached the code with the question;

function [jntangles] = dexik(tform)

dhparams=[125 pi/2 0 0;0 -pi/2 0 0;250 pi/2 0 0;0 -pi/2 0 0;

250 pi/2 0 0;0 -pi/2 0 0;100 0 0 0];

dextra = robotics.RigidBodyTree;

body1 = robotics.RigidBody('body1');

jnt1 = robotics.Joint('jnt1','revolute');

setFixedTransform(jnt1,dhparams(1,:),'dh');

body1.Joint = jnt1;

addBody(dextra,body1,'base')

body2 = robotics.RigidBody('body2');

jnt2 = robotics.Joint('jnt2','revolute');

body3 = robotics.RigidBody('body3');

jnt3 = robotics.Joint('jnt3','revolute');

body4 =robotics.RigidBody('body4');

jnt4 = robotics.Joint('jnt4','revolute');

body5 = robotics.RigidBody('body5');

jnt5 = robotics.Joint('jnt5','revolute');

body6 = robotics.RigidBody('body6');

jnt6 = robotics.Joint('jnt6','revolute');

body7 = robotics.RigidBody('body7');

jnt7 = robotics.Joint('jnt7','revolute');

setFixedTransform(jnt2,dhparams(2,:),'dh');

setFixedTransform(jnt3,dhparams(3,:),'dh');

setFixedTransform(jnt4,dhparams(4,:),'dh');

setFixedTransform(jnt5,dhparams(5,:),'dh');

setFixedTransform(jnt6,dhparams(6,:),'dh');

setFixedTransform(jnt7,dhparams(7,:),'dh');

body2.Joint = jnt2;

body3.Joint = jnt3;

body4.Joint = jnt4;

body5.Joint = jnt5;

body6.Joint = jnt6;

body7.Joint = jnt7;

addBody(dextra,body2,'body1')

addBody(dextra,body3,'body2')

addBody(dextra,body4,'body3')

addBody(dextra,body5,'body4')

addBody(dextra,body6,'body5')

addBody(dextra,body7,'body6')

ik = robotics.InverseKinematics('RigidBodyTree',dextra);

ik.SolverParameters.AllowRandomRestarts = true;

ig=homeConfiguration(dextra);

weights=[0.25 0.25 0.25 1 1 1];

release(ik)

[QSOL, SOLINFO] = step(ik, 'body7', tform, weights, ig);

jntangles=struct2table(QSOL);

jntangles=table2array(jntangles(:,2));

jntangles=rad2deg(jntangles);

end