public class JavaApplication2 {

    public static void main(String[] args) {
        float ff = 0.1f;
        double df = ff;
        double dd= 0.1;

        finePrint("0.1f=   ", ff);
        finePrint("0.1f->d=", df);
        finePrint("0.1d=   ", dd);
        finePrint("1.0 =   ", 1.0);
        finePrint("-1.0=   ", -1.0);
        
        
        System.out.println(ff);
        System.out.println(df);
    }
    
    public static void finePrint(String prepend, double v){
        String r = Long.toBinaryString( Double.doubleToRawLongBits(v) );
        while(r.length()<64){ 
            r = "-"+r;
        }
        System.out.println(prepend+r);
    }
    
    public static void finePrint(String prepend, float v){
        String r = Integer.toBinaryString( Float.floatToRawIntBits(v) );
        while(r.length()<32){
            r = "-"+r;
        }
        r = "   "+r;
        System.out.println(prepend+r);
    } 
}

0.1f=      --111101110011001100110011001101
0.1f->d=--11111110111001100110011001100110100000000000000000000000000000
0.1d=   --11111110111001100110011001100110011001100110011001100110011010
1.0 =   --11111111110000000000000000000000000000000000000000000000000000
-1.0=   1011111111110000000000000000000000000000000000000000000000000000
0.1
0.10000000149011612

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char** argv){
    double y = rand()/1.5;//тут rand чтобы компилятор не заоптимайзил
    printf("%g\n", y );
    return 0;
}

  400544:	55                   	push   %rbp
  400545:	48 89 e5             	mov    %rsp,%rbp
  400548:	48 83 ec 20          	sub    $0x20,%rsp
  40054c:	89 7d ec             	mov    %edi,-0x14(%rbp)
  40054f:	48 89 75 e0          	mov    %rsi,-0x20(%rbp)
  400553:	e8 f8 fe ff ff       	callq  400450 <rand@plt>;
  400558:	f2 0f 2a c0          	cvtsi2sd %eax,%xmm0
  40055c:	 f2 0f 10 0d 24 01 00 	movsd  0x124(%rip),%xmm1        # 400688 <_IO_stdin_used+0x10>
  400563:	00 
  400564: 	f2 0f 5e c1          	divsd  %xmm1,%xmm0
  400568:	f2 0f 11 45 f8       	movsd  %xmm0,-0x8(%rbp)
  40056d:	b8 80 06 40 00       	mov    $0x400680,%eax
  400572:	f2 0f 10 45 f8       	movsd  -0x8(%rbp),%xmm0
  400577:	48 89 c7             	mov    %rax,%rdi
  40057a:	b8 01 00 00 00       	mov    $0x1,%eax
  40057f:	e8 ac fe ff ff       	callq  400430 <printf@plt>;
  400584:	b8 00 00 00 00       	mov    $0x0,%eax
  400589:	c9                   	leaveq 
  40058a:	c3                   	retq   

400544:	55                   	push   %rbp
  400545:	48 89 e5             	mov    %rsp,%rbp
  400548:	48 83 ec 30          	sub    $0x30,%rsp
  40054c:	89 7d ec             	mov    %edi,-0x14(%rbp)
  40054f:	48 89 75 e0          	mov    %rsi,-0x20(%rbp)
  400553:	e8 f8 fe ff ff       	callq  400450 <rand@plt>;
  400558:	89 45 e8             	mov    %eax,-0x18(%rbp)
  40055b:	db 45 e8             	fildl  -0x18(%rbp)
  40055e:	dd 05 24 01 00 00    	fldl   0x124(%rip)        # 400688 <_IO_stdin_used+0x10>
  400564:	de f9                	fdivrp %st,%st(1)
  400566:	dd 5d f8             	fstpl  -0x8(%rbp)
  400569:	b8 80 06 40 00       	mov    $0x400680,%eax
  40056e:	48 8b 55 f8          	mov    -0x8(%rbp),%rdx
  400572:	48 89 14 24          	mov    %rdx,(%rsp)
  400576:	48 89 c7             	mov    %rax,%rdi
  400579:	b8 00 00 00 00       	mov    $0x0,%eax
  40057e:	e8 ad fe ff ff       	callq  400430 <printf@plt>;
  400583:	b8 00 00 00 00       	mov    $0x0,%eax
  400588:	c9                   	leaveq 
  400589:	c3                   	retq