sin (need to use in a loop for speed adjustment

[PMACKAY]

for i=1 to 55

???? sin(i) = 0.01, 0.02, 0.03 up to 0.08

next i

then i need a reverse of above

for i=55 to 1 step -1

???? sin(i) = 0.08, 0.07, 0.06 back to 0.01

next i

at various stages it needs to chang (the further from 55 then faster it gets  .eg _delay sin(i)  which is in range of 0 = 0.01 to 55 = 0.08    (gravity thing or stretch rubber band

pretty much needs to look like this

  <----------------------------------------------------------------------------------------------------------/   then reverse back to 0.01 so center of loop is slowest and furthest fastest
  0.01                      0.02                  0.03             0.04         0.05         0.06      0.07    0.08


thanks guys

[Petr]

Hi.
 
Maybe this?

i = .01

j! = _SINH(i)

PRINT SIN(j!)

[bplus]

OK the sin(x) function is at max when x = pi/2 here you want the max value to be .08.

Code: QB64: [Select]

1. SCREEN _NEWIMAGE(800, 600, 32)
2.  
3. 'when i = 1 to 55
4. 'want a = 0 to Pi/2
5. 'k*55 = pi/2
6. k = _PI(1 / 2) * (1 / 55) '<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< here is k for speed equation
7. 'at i = 55 want .08 speed
8. 'so
9. 'speed = .08 * SIN(k * i) '<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< here is equation
10.  
11. 'demo  and test plot
12. LINE (0, 100)-STEP(800, 0)
13. FOR i = 55 * 3 TO 4 * 55 * 3 STEP 55 * 3
14.     LINE (i, 0)-STEP(0, 600)
15.     _PRINTSTRING (i, 10), STR$(INT(i / 3))
16. NEXT
17.  
18. FOR i = 1 TO 220 'full cycle
19.     PSET (i * 3, 100 - .08 * SIN(k * i) * 500) 'test equation by plot of values magnified for human edification
20.     IF i MOD 5 = 0 THEN
21.         _PRINTSTRING (i * 3 - 12, 600 - .08 * SIN(k * i) * 6000), STR$(INT(.08 * SIN(k * i) * 100) / 100)
22.     END IF
23. NEXT
24.  

[PMACKAY]

Im not at home, it looks easy butsome unknown reason i cannot understand how to get it  into my code.... it keeps return 0 or goes into an error

Speed = _pi(1/2)*1/110
I have for k=1 to 110
Print 0.8 * sin (speed*k)
Next k
But only prints 0

It must be something im missing or a bug. I think more something im missing

So if i change 0.8 to 0.08 would this also work

Its a speed routine

Thank you b+   

[SMcNeill]

You've probably using DEFINT A-Z or DEFLNG A-Z in your code.  Make certain to DIM the variables involved As SINGLE/DOUBLE/FLOAT.

[bplus]

Code: QB64: [Select]

1. SCREEN _NEWIMAGE(800, 600, 32)
2.  
3. 'when i = 1 to 55
4. 'want a = 0 to Pi/2
5. 'k*55 = pi/2
6. k! = _PI(1 / 2) * (1 / 55) '<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< here is k for speed equation
7. 'at i = 55 want .08 speed
8. 'so
9. 'speed = .08 * SIN(k! * i%) '<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< here is equation
10.  
11. WHILE _KEYDOWN(27) = 0 'press escape to quite
12.     i% = i% + 1
13.     i% = i% MOD 110 'this keeps i between 0 and 110
14.  
15.     speed! = INT(.08 * SIN(k! * i%) * 100) / 100 '<<< this rounds to 100th's so can follow numbers
16.  
17.     'in code for speed use this
18.     'speed! = .08 * SIN(k! * i%)
19.  
20.     PRINT speed!; ", ";
21.     _LIMIT 5
22. WEND

I am wondering if you are working on a gravity like thing. Where there is change of speed there are forces at play and illustrating those could be effected by time but also by lengths or distance traveled over a set period of time like a loop with a limit which might be less jerky.

[bplus]

speed up, speed down: Hey! no fancy sin function ;)

Code: QB64: [Select]

1. SCREEN _NEWIMAGE(1200, 600, 32)
2.  
3. 'using single precsion default type
4. ox = 0: oy = 100: ow = 100: oh = 400: direction = 1: force = .1: dx = 0
5. WHILE _KEYDOWN(27) = 0
6.     CLS
7.     IF ox < 550 THEN dx = dx + force
8.     IF ox >= 550 THEN dx = dx - force
9.     IF ox < 0 THEN ox = 0: dx = 0
10.     IF ox > 1100 THEN ox = 1100: dx = 0
11.     ox = ox + dx
12.     LINE (ox, oy)-STEP(ow, oh), , BF
13.     LOCATE 1, 1: PRINT INT(dx)
14.     _DISPLAY
15.     _LIMIT 60
16. WEND
17.  

Hey this is cool accident trying to make above code work right:

Code: QB64: [Select]

1. SCREEN _NEWIMAGE(800, 600, 32)
2.  
3. 'using single precsion default type
4. ox = 0: oy = 100: ow = 100: oh = 400: direction = 1: force = .1: dx = 1
5. WHILE _KEYDOWN(27) = 0
6.     CLS
7.     dx = dx + direction * force 'the change of the change of x is constantly changing
8.     ox = ox + dx
9.     IF ox > 700 THEN ox = 699: direction = direction * -1: dx = -dx
10.     IF ox < 0 THEN ox = 1: direction = 1: dx = -dx
11.     LINE (ox, oy)-STEP(ow, oh), , BF
12.     LOCATE 1, 1: PRINT INT(dx)
13.     _DISPLAY
14.     _LIMIT 60
15. WEND
16.  

Watch what happens to bars, they never quite settle into any pattern.

                                             Warning: Lots of flashing lights going on here, epileptics BEWARE!

[Omerta7486]

First off, B+... Put a seizure warning on your second example! Please. I thought it looked cool, but an epileptic might feel otherwise! LOL

Second: Mackay, are you needing a parabolic jump arc, like gravity, or an elliptical loop like B+'s floating platform style example?

[bplus]

So that's where my morning went! ;-))