Subtraction of vectors subtracts whole vector with individual elements

Question

When I'm trying to calculate the value of DP, it subtracts the PCurrent matrix from each element of PGoal. What am I doing wrong?

OP4 = MatrixForm[{Cos[
      T1] (L1 + L2 Cos[T2] + L3 Cos[T2 + T3]), (L1 + L2 Cos[T2] + 
       L3 Cos[T2 + T3]) Sin[T1], L2 Sin[T2] + L3 Sin[T2 + T3]}];
OP4 = OP4 /. {L1 -> 0.3, L2 -> 0.3, L3 -> 0.15}
Print["OP4=", MatrixForm[OP4]];
OJTrans = 
  MatrixForm[{{(-(L1 + L2 Cos[T2] + L3 Cos[T2 + T3])) Sin[T1], 
     Cos[T1] ((-L2) Sin[T2] - L3 Sin[T2 + T3]), ((-L3) Cos[T1]) Sin[
       T2 + T3]}, {Cos[T1] (L1 + L2 Cos[T2] + L3 Cos[T2 + T3]), 
     Sin[T1] ((-L2) Sin[T2] - L3 Sin[T2 + T3]), ((-L3) Sin[T1]) Sin[
       T2 + T3]}, {0, L2 Cos[T2] + L3 Cos[T2 + T3], L3 Cos[T2 + T3]}}];
OJTrans = OJTrans /. {L1 -> 0.3, L2 -> 0.3, L3 -> 0.15}
ThetaInitial = {{0}, {Pi/4}, {Pi/2}};
PGoal = {{0.35}, {0.05}, {0.35}};
Print["PGO=", MatrixForm[PGoal]];
ThetaEstimate = ThetaInitial;
For[i = 1, i <= 5, i++,
  Print["IterationNumber", i];
  PCurrent = 
   OP4 /. {T1 -> ThetaEstimate[[1, 1]], T2 -> ThetaEstimate[[2, 1]], 
     T3 -> ThetaEstimate[[3, 1]]};
  Print["PCurrent=", MatrixForm[PCurrent]];
  DP = PGoal - PCurrent;
  Print["DP=", MatrixForm[DP]];
  ];

This is what i'm getting

SequenceForm["DP=", 
MatrixForm[{{
   0.35 - MatrixForm[{0.4060660171779821, 0., 0.3181980515339463}]}, {
   0.05 - MatrixForm[{0.4060660171779821, 0., 0.3181980515339463}]}, {
   0.35 - MatrixForm[{0.4060660171779821, 0., 0.3181980515339463}]}}]]

At a glance, I have to wonder about all the MatrixForm: See https://mathematica.stackexchange.com/questions/3098/why-does-matrixform-affect-calculations -- It would be easier to generate interest in other folks to investigate your problem with "a minimal working code example of your problem or your efforts". — Michael E2, Oct 14 '19 at 00:02

score 0 · Accepted Answer · answered Oct 14 '19 at 00:02

Do not include wrappers (e.g., MatrixForm) within definitions. Use MatrixForm[mat = {...}]rather than mat = MatrixForm[{ ... }]

Clear["Global`*"]

OP4 = {Cos[
     T1] (L1 + L2 Cos[T2] + L3 Cos[T2 + T3]), (L1 + L2 Cos[T2] + 
      L3 Cos[T2 + T3]) Sin[T1], L2 Sin[T2] + L3 Sin[T2 + T3]};
OP4 = OP4 /. {L1 -> 0.3, L2 -> 0.3, L3 -> 0.15};
Print["OP4=", MatrixForm[OP4]];

OJTrans = {{(-(L1 + L2 Cos[T2] + L3 Cos[T2 + T3])) Sin[T1], 
    Cos[T1] ((-L2) Sin[T2] - L3 Sin[T2 + T3]), ((-L3) Cos[T1]) Sin[
      T2 + T3]}, {Cos[T1] (L1 + L2 Cos[T2] + L3 Cos[T2 + T3]), 
    Sin[T1] ((-L2) Sin[T2] - L3 Sin[T2 + T3]), ((-L3) Sin[T1]) Sin[
      T2 + T3]}, {0, L2 Cos[T2] + L3 Cos[T2 + T3], L3 Cos[T2 + T3]}};
OJTrans = OJTrans /. {L1 -> 0.3, L2 -> 0.3, L3 -> 0.15};
ThetaInitial = {{0}, {Pi/4}, {Pi/2}};
PGoal = {{0.35}, {0.05}, {0.35}};
Print["PGO=", MatrixForm[PGoal]];

ThetaEstimate = ThetaInitial;
For[i = 1, i <= 5, i++, Print["IterationNumber", i];
  PCurrent = 
   OP4 /. {T1 -> ThetaEstimate[[1, 1]], T2 -> ThetaEstimate[[2, 1]], 
     T3 -> ThetaEstimate[[3, 1]]};
  Print["PCurrent=", MatrixForm[PCurrent]];
  DP = PGoal - PCurrent;
  Print["DP=", MatrixForm[DP]];];

Thanks. That helped. I'm just new to Mathematica so I'm still trying to find my way through it. — pinkpanta, Oct 14 '19 at 00:06

Subtraction of vectors subtracts whole vector with individual elements

1 Answers1