清华大学：《生物核磁共振波谱学》课程教学资源（参考资料，英文版）THE MATHEMATICS OF NMR

THE MATHEMATICS OF NMR Exponential Functions Differentials and Integrals Matrices Coordinate Transformations Convolutions The Fourier transform Exponential Functions The number 2.71828183 occurs so often in calculations that it is given the symbol e. When e is aised to the power x, it is often written exp(x) e=exp(x)=2.71828183 Logarithms based on powers of e are called natural logarithms. If Many of the dynamic NMR processes are exponential in nature. For example, signals decay exponentially as a function of time. It is therefore essential to understand the nature of exponential curves. Three common exponential functions are y=e-X/t y=(1-e-x/t)

THE MATHEMATICS OF NMR -------------------------------------------------------------------------------- Exponential Functions Trigonometric Functions Differentials and Integrals Vectors Matrices Coordinate Transformations Convolutions Imaginary Numbers The Fourier Transform -------------------------------------------------------------------------------- Exponential Functions The number 2.71828183 occurs so often in calculations that it is given the symbol e. When e is raised to the power x, it is often written exp(x). e x = exp(x) = 2.71828183x Logarithms based on powers of e are called natural logarithms. If x = ey then ln(x) = y, Many of the dynamic NMR processes are exponential in nature. For example, signals decay exponentially as a function of time. It is therefore essential to understand the nature of exponential curves. Three common exponential functions are y = e-x/t y = (1 - e-x/t)

y=(1 where t is a constant The basic trigonometric functions sine and cosine cos(x) describe sinusoidal functions which are 90 out of phase The trigonometric identities are used in geometric calculations

y = (1 - 2e-x/t) where t is a constant. Trigonometric Functions The basic trigonometric functions sine and cosine describe sinusoidal functions which are 90o out of phase. The trigonometric identities are used in geometric calculations

hypotenuse Sin(e)=Opposite /Hypotenuse Cos( 0)=Adjacent/Hypotenuse Tan()=Opposite / Adjacent The function sin(x)/x occurs often and is called sinc(x) sinc( X) Differentials and Integrals a differential can be thought of as the slope of a function at any point. For the function the differential of y with respect to x is y An integral is the area under a function between the limits of the integral

Sin() = Opposite / Hypotenuse Cos() = Adjacent / Hypotenuse Tan() = Opposite / Adjacent The function sin(x) / x occurs often and is called sinc(x). Differentials and Integrals A differential can be thought of as the slope of a function at any point. For the function the differential of y with respect to x is An integral is the area under a function between the limits of the integral

An integral can also be considered a summation; in fact most integration is performed by computers by adding up values of the function between the integral limits A vector is a quantity having both a magnitude and a direction. The magnetization from nuclear spins is represented as a vector emanating from the origin of the coordinate system. Here it is along the +z axis In this picture an the vector is in the XY plane between the +X and +Y axes. The vector has X and Y components and a magnitude equal to (X2+Y2)12 Matrices A matrix is a set of numbers arranged in a rectangular array. This matrix has 3 rows and 4 columns and is said to be a 3 by 4 matrix

An integral can also be considered a summation; in fact most integration is performed by computers by adding up values of the function between the integral limits. Vectors A vector is a quantity having both a magnitude and a direction. The magnetization from nuclear spins is represented as a vector emanating from the origin of the coordinate system. Here it is along the +Z axis. In this picture the vector is in the XY plane between the +X and +Y axes. The vector has X and Y components and a magnitude equal to ( X2 + Y2 )1/2 Matrices A matrix is a set of numbers arranged in a rectangular array. This matrix has 3 rows and 4 columns and is said to be a 3 by 4 matrix

123|7 45618 9 543 To multiply matrices the number of columns in the first must equal the number of rows in the second. Click sequentially on the next start buttons to see the individual steps associated with the 1231751_「50 456184 9 1x7=7 2x8=16 3X9=27 50 123175「5022 45618412258 93 X5=20 5x4=20 6x3=18 58 Coordinate transformations a coordinate transformation is used to convert the coordinates of a vector in one coordinate system(XY) to that in another coordinate system(X"Y")

To multiply matrices the number of columns in the first must equal the number of rows in the second. Click sequentially on the next start buttons to see the individual steps associated with the multiplication. Coordinate Transformations A coordinate transformation is used to convert the coordinates of a vector in one coordinate system (XY) to that in another coordinate system (X"Y")

Convolution The convolution of two functions is the overlap of the two functions as one function is passed over the second. The convolution symbol is. The convolution of h(t) and g(t) is defined mathematically as The above eq - n is depicted for rectangular shaped h(t)and g(t) functions in this animation g(t) f(t) Imaginary numbers are those which result from calculations involving the square root of-1 Imaginary numbers are symbolized by i A complex number is one which has a real (RE)and an imaginary(IM)part. The real and imaginary parts of a complex number are orthogonal Two useful relations between complex numbers and exponentials are e"ix=cos(x)+isin(x) Ix =cos(x)-isin(x)

Convolution The convolution of two functions is the overlap of the two functions as one function is passed over the second. The convolution symbol is . The convolution of h(t) and g(t) is defined mathematically as The above equation is depicted for rectangular shaped h(t) and g(t) functions in this animation. Imaginary Numbers Imaginary numbers are those which result from calculations involving the square root of -1. Imaginary numbers are symbolized by i. A complex number is one which has a real (RE) and an imaginary (IM) part. The real and imaginary parts of a complex number are orthogonal. Two useful relations between complex numbers and exponentials are e +ix = cos(x) +isin(x) and e -ix = cos(x) -isin(x)

Fourier Transforms The Fourier transform(FT) is a mathematical technique for converting time domain data to frequency domain data, and vice versa The Fourier transform will be explained in detail in later Chapters Time 可 Frequency

Fourier Transforms The Fourier transform (FT) is a mathematical technique for converting time domain data to frequency domain data, and vice versa. The Fourier transform will be explained in detail in later Chapters