Christian Wolinski

MaplePrimes Activity

These are replies submitted by Christian Wolinski

Are we to assume that k stands for K and i stands for I?
Also notice you are using e^(-k*h), e^(-k*z). That should be exp(-k*h) and exp(-k*z).

Have you made any progress with this equation?

I am assuming you are trying to compare dates to determine which comes first. Depending on ordering DayCount is positive or negative. Maybe you can use this.

@Stretto Maybe it will be of use. If you want to color code the entire vertical of a bar to your coloring scheme then I suppose you must subdivide that bar (yourself). Matrixplot will not do that I believe.

@acer Did not see that.

One question:

solve(And(y < -1, y < x, 0 < (2*x)/(x^2 - 1), x < 1), y);
solve(And(y < -1, y < x, 0 < (2*x)/(x^2 - 1), x < 1), x);
solve(And(y < -1, y < x, 0 < (2*x)/(x^2 - 1), x < 1), x) assuming y<-1;

Is there some other way to induce the answer in the above?

How do you know that:


x*diff(f(x,y),x)+y*diff(f(x,y),y) = x*y*ln(x*y),
x^2*diff(f(x,y),x,x)+y^2*diff(f(x,y),y,y) = x*y

gives the complete solution?


 map(`@`(abs, lhs - rhs), EQ)

this will compute the absolute values of the errors of the equations in EQ.

map(`@`(evalf, subs), sols, ...

this will substitute each solution in sols into the above, and use evalf on it.

fnormal will annihilate numeric error smaller than 10^(-(Digits-4)).

Solutions in sols generate error no greater than 10^(-56).

Out of curiosity: which Intel Xeon, what motherboard?

@Joe Riel What if n is intended to be integer?

@arashghgood You are looking for a solution sol2 in the range Re(K)=0..1, Im(K)=4..5. I think that "solution" appears when cosh(Q)=0. Otherwise simply use this code:

  EQ := {Q = sqrt(K^2 - 6.283185308*I), (K*(Q*sinh(K)*cosh(Q)
   - K*cosh(K)*sinh(Q))*(7.135575944*K^2 + 1)
   - 0.0004077471968*K^2*Q*(K^2 + Q^2)
   + 0.0001019367992*Q*(5*K^4 + 2*K^2*Q^2 + Q^4)*cosh(K)*cosh(Q)
   - 0.0001019367992*K*(K^4 + 6*K^2*Q^2 + Q^4)*sinh(K)*sinh(Q))/(K^2*Q*cosh(Q)
  ) = 0};
  Digits := 60;
  sols := {};
  do sol1 := {fsolve}(EQ, {K, Q}, {K = 0 .. 5 + 14*I}, complex, fulldigits, 
    avoid = sols);
    if type(eval('sol1', 2), set(specfunc(anything, fsolve))) then
    end if;
    sols := `union`(sols, sol1);
  end do;
  map(`@`(evalf, subs), sols, map(`@`(abs, lhs - rhs), EQ));
  fnormal(%, Digits - 4);

Fine code, but surprisingly slow. Serial rather than iterative process is needed. Simplex package does not seem up to the task. (?) Are there alternatives?

@mmcdara Yes, thank You. This is the idea I was recollecting. This can be implemented as a masking of a fixed texture by a projection of an object.

@Kitonum Maplesoft does provide older versions to be used in place of your current one. Does this mean you can have all of them installed, or must you uninstall the other to use just one?

@Kitonum So there is no hope for it with 64 bit installation? Can I have 32bit and 64bit installs simultaneously?

You need to look at the last line and decide what you were trying to do:


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