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I am having trouble programming the SOLVE and fsolve functions, and I am not sure of what I am doing wrong. I can run solve on the HP Prime, but I can't programmatically solve the equation.
[Image: solve1.png]

[9/17/19. Replaced tinypic image]

EDIT 6/4/18 corrected error in code with the radius, but still can't get code to work.

Code:

EXPORT OldAAngleSetting,theta,radius,x,q,v;

EXPORT SolveProgramExamples()

BEGIN

OldAAngleSetting:=AAngle; //save apps angle mode setting

AAngle:=1; //Switch to apps radian angle mode

// SOLVE Example ----------------------------------------

//initialize variables

X:=0;

theta:=0;

//input

V:=2;

R:=0.75;

Q:=3.1;

Solve.SOLVE(X-SIN(X)=2*Q/(V*R^2),X,3);

theta:=X;

PRINT();

PRINT("SOLVE example");

PRINT("X="+X);

PRINT("theta="+theta);

// fsolve Example ------------------------------

//initialize variables

x:=0;

theta:=0;

//input

v:=2;

radius:=0.75;

q:=3.1;

theta:=CAS("fsolve(x-SIN(x)=2*q/(v*radius^2),x=3)");

PRINT(" ");

PRINT("fsolve example");

PRINT("x="+x);

PRINT("theta="+theta);

AAngle:=OldAAngleSetting; //restore previous apps angle mode setting

END;

The value returned by SOLVE was not stored.
The CAS has a 'radius' command, so it will not be able to directly capture the exported variable of the program.

Code:

EXPORT OldAAngleSetting,theta,rads,q,v; //← x isn't necessary, radius → rads

EXPORT SolveProgramExamples()

BEGIN

OldAAngleSetting:=AAngle; //save apps angle mode setting

AAngle:=1; //Switch to apps radian angle mode

// SOLVE Example ----------------------------------------

//initialize variables

theta:=0;

//input

V:=2;

R:=0.75;

Q:=3.1;

X:=Solve.SOLVE(X-SIN(X)=2*Q/(V*R^2),X,3); //←

theta:=X;

PRINT();

PRINT("SOLVE example");

PRINT("X="+X);

PRINT("theta="+theta);

// fsolve Example ------------------------------

//initialize variables

theta:=0;

//input

v:=2;

rads:=0.75;

q:=3.1;

theta:=fsolve("x-SIN(x)=2*q/(v*rads^2),x=3"); //←

PRINT(" ");

PRINT("fsolve example");

PRINT("x="+theta); // ←

PRINT("theta="+theta);

AAngle:=OldAAngleSetting; //restore previous apps angle mode setting

END;

If you persist in using "radius", you can evade the name resolution CAS-Home by manufacturing the data in strings before sending it to the CAS, in this way it can be done for similar cases.

Code:

theta:=fsolve(EVAL("x-SIN(x)=2*q/(v*"+radius+"^2),x=3"));

Thanks. Your "fsolve" equation changes also work with the "solve" command, which is what I initially wanted to do. I used "radius" to differentiate the pipe radius from the hydraulic radius "r". Geez...

Gene222

Carlos295pz

Carlos295pz

Gene222