I have to draw a graph y = cos(x2 x 1) interval: [-π/2,π/2]. I have the graph without the interval, just making calculations with the screen resolution 320 x 200.

This is my code so far:

;------------------------------------------------------------------------
%include 'yasmmac.inc'  
org 100h                       

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
section .text                   ; code starts here
   startas:
      call procSetGraphicsMode

     xor  di, di     ; Y
   .vertical:
     mov  si, 160    ; X
     mov  cl, 15     ; Color
     call procPutPixel
     inc  di
     cmp  di, 199    ; MaxY
     jbe  .vertical

     xor  si, si     ; X
   .horizontal:        
     mov  di, 100    ; Y
     mov  cl, 15     ; Color
     call procPutPixel
     inc  si
     cmp  si, 319    ; MaxX
     jbe  .horizontal

  ; y = di
  ; x = si
  mov si, 320
  mov di, 100

      xor   si, si          ; X
    fninit
    fld1                  ; CONST 1
.loop:
    mov   [valueX], si    ; X
    fild  word [valueX]   ; st0 = X
    fmul  st0             ; st0 = X^2
    fiadd word [valueX]   ; st0 = X^2   X
    fadd  st0, st1        ; st0 = X^2   X   1
    fcos                  ; st0 = cos(X^2   X   1)         [-1, 1]
    fimul word [scaleY]
    fistp word [y]        ; {-1,0, 1}
    mov   di, 100         ; Y
    add   di, [y]         ; -> Y={99,100,101}
    mov   cl, 4           ; Color
    call  procPutPixel
    inc   si
    cmp   si, 319
    jbe   .loop


   call procWaitForEsc 
  exit
      

%include 'yasmlib.asm'
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
section .data                   ; data
     R:
     dd  50.0

   value1: 
      dd  0.0
   value2:
      dd  0.0
   value3:
      dd 1.0

   valueX:  
      dw 0
   
   scaleY: 
       dw 60
          
     x: 
     dw  0
     y:
     dw 0
     
     N:
     dw 360  
     
  
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
section .bss            

This code section draws a coordinate plane and the graph, not in the given interval [-π/2,π/2].

What I want the program to do is to draw that interval within the interval [-π/2,π/2]. So it would look something like this:

I need somehow scale my X so that the graph would be within the intervals.

I was thinking to make the starting point of X in the center (160), but I can't imagine, how to move to both sides (negative - towards -π/2 and positive - towards π/2). I have tried to explain that as clearly as I could.

If more information is needed, I will try to edit the question.

CodePudding user response：

graph y = cos(x2 x 1)

I am confused now: is it cos(x2 x 1) or cos(x^2 x 1) that you want to draw? The