Question

I’m trying to convert some algorithms to another language and am stuck on a few lines of code. The language I’m converting from is actionscript and converting it to lua.

I came across this line

return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b

is this the same as

s = s*1.525
return c/2*(t*t*((s+1)*t - s)) + b

or is it the same as

newS = s*1.525
return c/2*(t*t*((newS+1)*t - s)) + b

so once the *= is called, is s changed throughout the function, so every instance of s is the new value or is it only calculated once and s retains it’s value from before?

Any help would be appreciated. Thanks!

Answer 1

The assignment operators are evaluated from right to left on the same level of nesting. As your original statement has s*=1.25 enclosed into parentheses the *= assignment is executed in advance of addition of 1, multiplication by t, e.t.c., So, your first variant is the correct one.